Polyorganosiloxane latex, graft copolymer using the same, thermoplastic resin composition, and molded body

ABSTRACT

A variety of molded bodies having high weatherability, impact resistance, designability, and the like, and a polyorganosiloxane latex and a graft copolymer used as the raw material therefor are provided. A polyorganosiloxane latex having a mass average particle diameter (Dw) of a polyorganosiloxane particle of 100 to 200 nm, and a ratio of the mass average particle diameter (Dw) to a number average particle diameter (Dn) (Dw/Dn) of 1.0 to 1.7. A polyorganosiloxane-containing vinyl-based copolymer (g) obtained by polymerizing one or more vinyl-based monomers in the presence of the latex. A graft copolymer (G) obtained by graft polymerizing one or more vinyl-based monomers in the presence of the copolymer. A thermoplastic resin composition including the graft copolymer (Ga) and a thermoplastic resin (Ha) except for the graft copolymer (Ga). A molded body obtained by molding the resin composition. A lamp housing for vehicle lighting including the molded body obtained by molding the composition.

TECHNICAL FIELD

The present invention relates to a polyorganosiloxane latex, a graftcopolymer using the polyorganosiloxane latex, a thermoplastic resincomposition, and a molded body.

BACKGROUND ART

Polyorganosiloxane latexes are widely used as raw materials for resinadditives, fiber treatment agents, mold release agents, cosmetics,antifoaming agents, additives for a coating material, and the like.Various methods have been proposed as the method of producing apolyorganosiloxane latex. For example, Patent Literature 1 and PatentLiterature 2 describe polyorganosiloxane latexes obtained by emulsionpolymerizing organosiloxane in an aqueous medium.

Polyorganosiloxane in a latex exhibits different properties depending onthe particle diameter. When a polyorganosiloxane latex is used as a rawmaterial for resin additives, fiber treatment agents, mold releaseagents, cosmetics, antifoaming agents, additives for a coating material,and the like, a polyorganosiloxane latex having the particle diameteroptimal to the application is required in order to exhibit theperformance which each of these target products requires. Thus,polyorganosiloxane having a controlled particle diameter and particlediameter distribution is useful.

For polyorganosiloxane contained in the latexes produced by the methodsdescribed in these Patent Literatures, the mass average particlediameter (Dw) is 150 to 800 nm, particle diameter distribution (Dw/Dn)expressed as a ratio of the mass average particle diameter (Dw) to thenumber average particle diameter (Dn) is 1.2 or less (Patent Literature1), the number average particle diameter is 100 nm or less, and thestandard deviation of the particle diameter is 70 nm or less (PatentLiterature 2) as described in these Patent Literatures. Unfortunately,the methods described in these Patent Literatures actually havedifficulties to obtain polyorganosiloxane having the mass averageparticle diameter of 100 nm to 200 nm and Dw/Dn of 1.7 or less.

Automobile lights such as a taillight, a brake light, and a headlightfor automobiles mainly include a lens made of a transparent resin suchas a polymethyl methacrylate (PMMA) resin and a polycarbonate (PC) resinand a housing that supports the lens. Among these, the housing ispartially exposed to the sunlight outdoors. For this reason, the housingformed of a material having high weatherability has been desired inthese days.

In production of the automobile light in the related art, the lens isbonded to the housing with a hot-melt adhesive, and integrated. Toincrease productivity, recently, the lens is bonded to the housing by avibration welding method in some cases. Here, the vibration weldingmethod is a welding method utilizing frictional heat in which in thestate where the periphery end of the lens is pressed against theperiphery end of the housing, vibration having a amplitude of 0.5 mm to2.0 mm and the number of vibration of 200 Hz to 300 Hz is applied togenerate frictional heat between the lens and the housing; thereby, thelens and the housing are fused, bonded, and integrated. In such avibration welding method, the finished bonded portion of the lens andthe housing needs to have a good appearance.

For the material for vibration welding, a thermoplastic resincomposition containing a graft copolymer containing a compositerubber-based polymer consisting of polyorganosiloxane including vinylpolymerizable functional group-containing siloxane and alkyl(meth)acrylate rubber is disclosed.

A thermoplastic resin molded body for automobile parts and casings for avariety of electrical appliances may be subjected to a plating surfacetreatment for forming a metallic film made of a material such as copper,chromium, and nickel on the surface of the molded body to enhancedesignability and other functionalities. Moreover, a metallizationtreatment for forming a metallic film of aluminum, chromium, or the like(thickness of several dozen nanometers to several hundred nanometers)may be performed on the surface of the thermoplastic resin molded bodyby a vacuum deposition method, a sputtering method, or the like.

In the latter metallization treatment, to enhance the brightness of themolded body, an undercoat layer is usually formed by coating or plasmapolymerization in advance before performing metallization treatment.Further, to protect the metallic film obtained by metallizationtreatment, a top coat layer composed of a silicon-based material or thelike is usually formed.

Thus, conventional metallization treatment needs many steps, a dedicatedapparatus, and an expensive treatment agent, while the so-called “directdeposition method” eliminating the step for forming the undercoat layeris used these days. The designability of the molded body obtained by thedirect deposition method easily changes according to the kind of resinmaterials and the state of the surface of the molded body. For thisreason, one of important problems is to stably maintain a beautifulbright appearance of the surface without fogging.

For the resin material suitable for the direct deposition, PatentLiterature 3 discloses a thermoplastic resin containing arubber-containing graft copolymer prepared by graft polymerizing avinyl-based monomer with a rubber-based polymer having specific particlediameter distribution. Moreover, Patent Literature 3 discloses athermoplastic resin composition in which the mass average particlediameter of the rubber-based polymer and the proportion of the component(% by mass) have a specific relationship.

Meanwhile, automobile members tend to be lighter these days. For thisreason, the automobile members need to have higher physical propertiessuch as impact resistance than ever. In addition to high heatresistance, the level of a demand for a beautiful bright appearance hasbeen increased year after year. Unfortunately, the thermoplastic resincomposition disclosed in Patent Literature 3 cannot sufficiently meetthe recent demand for high brightness and impact resistance.

Further, recent thermoplastic resin compositions used for vehiclemembers and construction members need high mechanical strength under alow temperature. Efforts have been made so far to improve the surfaceappearance and impact resistance of the molded article made from acomposite rubber-based graft copolymer prepared from apolyorganosiloxane rubber and an acrylic rubber in combination and theperformance of impact resistance. For example, Patent Literature 4discloses a thermoplastic resin composition comprising apolyorganosiloxane/acrylic composite rubber-based graft copolymer inwhich the average particle diameter is 10 to 70 nm and the proportion ofparticles having a particle diameter more than 100 nm is 20% or lessbased on the total particle volume. Such a resin composition, however,cannot achieve the performance that sufficiently meets the recentdemand.

CITATION LIST Patent Literature

-   Patent Literature 1: JP2007-321066A-   Patent Literature 2: JP05-194740A-   Patent Literature 3: JP2003-128868A-   Patent Literature 4: JP06-25492A

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a variety of moldedbodies (in particular, automobile parts, casings for a variety ofelectrical appliances, construction members and the like) having highweatherability, impact resistance, designability and the like; and apolyorganosiloxane latex and a graft copolymer as raw materials forthese molded bodies.

Solution to Problem

The problems above are solved by aspects [1] to [24] according to thepresent invention below.

[1] A polyorganosiloxane latex, wherein a mass average particle diameter(Dw) of a polyorganosiloxane particle is 100 to 200 nm, and wherein aratio (Dw/Dn) of the mass average particle diameter (Dw) to a numberaverage particle diameter (Dn) of the particle is 1.0 to 1.7.[2] The polyorganosiloxane latex according to [1], wherein a standarddeviation of the mass average particle diameter (Dw) of thepolyorganosiloxane particle is 0 to 80.[3] The polyorganosiloxane latex according to [1] or [2], wherein aproportion of the polyorganosiloxane particle having a particle diameterless than 50 nm is 5% by mass or less based on the total amount of theparticle, and wherein a proportion of the polyorganosiloxane particlehaving a particle diameter of 300 nm or more is 20% by mass or lessbased on the total amount of the particle.[4] A polyorganosiloxane-containing vinyl-based copolymer obtained bypolymerizing one or more vinyl-based monomers in the presence of thepolyorganosiloxane latex according to any one of [1] to [3].[5] The polyorganosiloxane-containing vinyl-based copolymer according to[4], wherein a mass average particle diameter (Dw) of a particle in thepolyorganosiloxane-containing vinyl-based copolymer is 110 nm to 800 nm,and a ratio (Dw/Dn) of the mass average particle diameter (Dw) to anumber average particle diameter (Dn) of the particle is 1.0 to 2.0.[6] The polyorganosiloxane-containing vinyl-based copolymer according to[4] or [5], wherein the vinyl-based monomer is an acrylic acid ester.[7] A graft copolymer (G) obtained by graft polymerizing one or morevinyl-based monomers in the presence of thepolyorganosiloxane-containing vinyl-based copolymer according to any oneof [1] to [4].[8] The graft copolymer (G) according to [7], wherein a molded bodyobtained by molding the following composition exhibits the followingperformance (1) and (2) when evaluated under the following measurementconditions:

(1) a Charpy impact strength at 23° C. is 6 kJ/m² or more, and

(2) a diffuse reflectance is 5% or less.

<Test Piece Production Condition>

(a) 33 parts by mass of a graft copolymer (Ga),

(b) 9 parts by mass of an acrylonitrile•styrene copolymer including 25%by mass of an acrylonitrile unit and 75% by mass of a styrene unit andhaving a reduced viscosity (ηsp/c) of 0.40 dL/g in anN,N-dimethylformamide solution of 0.2 g/dL at 25° C.,

(c) 9 parts by mass of an acrylonitrile-styrene copolymer including 28%by mass of an acrylonitrile unit and 72% by mass of a styrene unit andhaving a reduced viscosity of 0.62 dL/g in an N,N-dimethylformamidesolution of 0.2 g/dL at 25° C.,

(d) 50 parts by mass of an acrylonitrile-styrene-N-phenylmaleimidecopolymer including 22% by mass of an acrylonitrile unit, 55% by mass ofa styrene unit, and 23% by mass of an N-phenylmaleimide unit and havinga reduced viscosity of 0.66 dL/g in an N,N-dimethylformamide solution of0.2 g/dL at 25° C.,

(e) 0.5 parts by mass of ethylenebisstearylamide,

(f) 0.03 parts by mass of silicone oil, and

(g) 0.05 parts by mass of carbon black.

These seven materials (a) to (g) above are blended, and kneaded using avolatilizing extruder (TEX-30α made by The Japan Steel Works, Ltd.)whose barrel is heated to a temperature of 260° C. to obtain pellets;the pellets are molded using a 4-ounce injection molding machine (madeby The Japan Steel Works, Ltd.) in conditions of a cylinder temperatureof 260° C. and a mold temperature of 60° C. to obtain a test piece 1 (alength of 80 mm, a width of 10 mm and a thickness of 4 mm); and aplate-like molded body 2 (a length of 100 mm, a width of 100 mm and athickness of 2 mm) is obtained in the same manner as above in conditionsof a cylinder temperature of 260° C., a mold temperature of 60° C., andan injection rate of 5 g/sec.

<Charpy Impact Strength Measurement Condition>

Measurement is conducted on a V-notched test piece 1 that is left undera 23° C. atmosphere for 12 hours or more by a method according to ISO179.

<Diffuse Reflectance Measurement Condition>

A 50 nm aluminum film is formed (direct deposition) on the surface ofthe molded body 2 by a vacuum deposition method (VPC-1100 made byULVAC-PHI, Inc.) in conditions of a degree of vacuum of 6.0×10⁻³ Pa anda film forming rate of 10 angstroms/sec; and a diffuse reflectance (%)of the obtained molded body is measured using a reflectance meter(TR-1100AD made by Tokyo Denshoku Co., Ltd.).

[9] The graft copolymer (Ga) according to [8], comprising 5 to 25% bymass of polyorganosiloxane based on 100% by mass of apolyorganosiloxane-containing vinyl-based copolymer, wherein a mixtureof a vinyl cyanide-based monomer and an aromatic vinyl-based monomer isgraft polymerized with the polyorganosiloxane-containing vinyl-basedcopolymer, wherein the polyorganosiloxane-containing vinyl-basedcopolymer has a mass average particle diameter (Dw) of 120 to 200 nm,wherein a proportion of a particle having a particle diameter of 100 nmor less is 15% by mass or less of a total amount of the particle, andwherein a proportion of the particle having a particle diameter of 400nm or more is 1% by mass or less of the total amount of the particle.[10] The graft copolymer (Ga) according to [8] or [9], wherein thepolyorganosiloxane contains 0.5 to 5 parts by mass of a componentderived from a siloxane-based crosslinking agent based on 100 parts bymass of the organosiloxane.[11] A thermoplastic resin composition (Ia) including the graftcopolymer (Ga) according to any one of [8] to [10], and a thermoplasticresin (Ha) except for the graft copolymer (Ga).[12] The thermoplastic resin composition (Ia) according to [11], whereinthe thermoplastic resin (Ha) is a copolymer including 0 to 40% by massof a vinyl cyanide-based monomer unit, 40 to 80% by mass of an aromaticvinyl-based monomer unit, and 0 to 60% by mass of another monomer unitwhose monomer is copolymerizable with these monomers.[13] A molded body obtained by molding the thermoplastic resincomposition (Ia) according to [11] or [12].[14] A lamp housing for vehicle lighting including a molded bodyobtained by molding the thermoplastic resin composition (Ia) accordingto [11] or [12].[15] The graft copolymer (G) according to [7], wherein a molded bodyobtained by molding the following composition exhibits the followingperformance (1) and (2) when evaluated under the following measurementconditions:

(1) L* is 24 or less, and

(2) a Charpy impact strength at −30° C. is 6 kJ/m² or more.

<Test Piece Production Condition>

(a) 42 parts by mass of a graft copolymer (Gb),

(b) 58 parts by mass of an acrylonitrile-styrene copolymer including 34%by mass of an acrylonitrile unit and 66% by mass of a styrene unit andhaving a reduced viscosity (ηsp/c) of 0.62 dL/g in anN,N-dimethylformamide solution of 0.2 g/dL at 25° C.,

(c) 0.3 parts by mass of ethylenebisstearylamide, and

(d) 0.5 parts by mass of carbon black.

These four materials (a) to (d) above are blended, and kneaded using avolatilizing extruder (made by Ikegai Corp., PCM-30) whose barrel isheated to a temperature of 230° C. to obtain pellets; the pellets aremolded using a 4-ounce injection molding machine (made by The JapanSteel Works, Ltd.) in conditions of a cylinder temperature of 230° C.and a mold temperature of 60° C. to obtain a test piece 3 (length of 80mm, width of 10 mm, and thickness of 4 mm) and a tensile test piece 4(length of 170 mm, width of 20 mm, and thickness of 4 mm).

<Charpy Impact Strength Measurement Condition>

Measurement is conducted on a V-notched test piece 3 that is left undera −30° C. atmosphere for 12 hours or more by a method according to ISO179.

<L* Measurement Condition>

L* is measured for the tensile test piece 4 using a spectrophotometerCM-508D made by Konica Minolta Sensing, Inc. on a side opposite to agate.

[16] The graft copolymer (Gb) according to [15], comprising 15 to 80% bymass of polyorganosiloxane based on 100% by mass of apolyorganosiloxane-containing vinyl-based copolymer, wherein a mixtureof a vinyl cyanide-based monomer and an aromatic vinyl-based monomer isgraft polymerized with the polyorganosiloxane-containing vinyl-basedcopolymer, wherein the polyorganosiloxane-containing vinyl-basedcopolymer has a mass average particle diameter (Dw) of 110 to 250 nm,wherein a proportion of a particle having a particle diameter less than100 nm is 20% by mass or less based on the total amount of the particle,and wherein a proportion of the particle having a particle diameter of300 nm or more is 20% by mass or less based on the total amount of theparticle.[17] The graft copolymer (Gb) according to [15] or [16], wherein thepolyorganosiloxane contains 0.5 to 3 parts by mass of a componentderived from a siloxane-based crosslinking agent based on 100 parts bymass of organosiloxane.[18] A thermoplastic resin composition (Ib) including the graftcopolymer (Gb) according to any one of [15] to [17] and a thermoplasticresin (Hb) except for the graft copolymer (Gb).[19] The thermoplastic resin composition (Ib) according to [18], whereinthe thermoplastic resin (Hb) is a copolymer including 0 to 40% by massof a vinyl cyanide-based monomer unit, 40 to 80% by mass of an aromaticvinyl-based monomer unit, and 0 to 60% by mass of another vinyl-basedmonomer unit whose monomer is copolymerizable with these monomers.[20] A molded body obtained by molding the thermoplastic resincomposition (Ib) according to [18] or [19].[21] A method of producing a polyorganosiloxane latex, the methodcomprising a step of dropping an emulsion (B) comprising organosiloxane,an emulsifier, and water into a water-based medium (A) comprising water,an organic acid catalyst, and an inorganic acid catalyst; and a step ofperforming polymerization, wherein a total amount of the organic acidcatalyst and the emulsifier is 0.5 to 6 parts by mass based on 100 partsby mass of the organosiloxane, wherein the pH of the water-based medium(A) measured at 25° C. is within the range of 0 to 1.2, and wherein thedropping rate of the emulsion (B) is a rate such that an amount oforganosiloxane to be fed is 0.5 [parts by mass/min] or less when a totalamount of organosiloxane to be used is 100 parts by mass.[22] The method according to [21], wherein the total amount of theorganic acid catalyst and the emulsifier is 0.5 to 6 parts by mass basedon 100 parts by mass of organosiloxane, and the pH of the water-basedmedium (A) measured at 25° C. is within the range of 0 to 1.0.[23] The method according to [21] or [22], wherein the dropping rate ofthe emulsion (B) is a rate such that the rate of organosiloxane to befed is 0.5 parts by mass/min or less.[24] The method according to [22] or [23], wherein the organic acidcatalyst contains at least one or more selected from the groupconsisting of aliphatic sulfonic acids, aliphatic-substitutedbenzenesulfonic acids, and aliphatic-substituted naphthalenesulfonicacids.

Advantageous Effects of Invention

The present invention provides a variety of molded bodies (inparticular, automobile parts, casings for a variety of electricalappliances, construction members and the like) having highweatherability, impact resistance, designability and the like; and apolyorganosiloxane latex and a graft copolymer as raw materials forthese molded bodies.

DESCRIPTION OF EMBODIMENTS [Polyorganosiloxane Latex]

In the polyorganosiloxane latex according to the present invention, themass average particle diameter (Dw) of the polyorganosiloxane particleis 100 to 200 nm, and the ratio (Dw/Dn) of the mass average particlediameter (Dw) to the number average particle diameter (Dn) is 1.0 to1.7. Since Dw and Dw/Dn are in these ranges, the molded body comprisinga blend of the polyorganosiloxane-containing vinyl-based copolymer andthe graft copolymer exhibits high brightness, color developability, andimpact resistance. Dw is preferably 100 to 190 nm. Dw/Dn is preferably1.0 to 1.3.

In the polyorganosiloxane latex, the standard deviation in the massaverage particle diameter (Dw) of the polyorganosiloxane particle ispreferably 0 to 80.

In the polyorganosiloxane particle in the polyorganosiloxane latex,preferably, the proportion of the particle having a particle diameterless than 50 nm is 5% by mass or less based on the total amount of theparticle, and the proportion of the particle having a particle diameterof 300 nm or more is 20% by mass or less based on the total amount ofthe particle.

The polyorganosiloxane latex according to the present invention isproduced, for example, by dropping an emulsion (B) includingorganosiloxane, an emulsifier, and water into a water-based medium (A)including water, an organic acid catalyst, and an inorganic acidcatalyst, and performing polymerization. For a specific productioncondition, for example, the total amount of the organic acid catalystand the emulsifier is 0.5 to 6 parts by mass based on 100 parts by massof organosiloxane, the pH of the water-based medium (A) measured at 25°C. is within the range of 0 to 1.2, and the dropping rate of theemulsion (B) is a rate such that the amount of organosiloxane to be fedis 0.5 [parts by mass/min] or less when a total amount of organosiloxaneto be used is 100 parts by mass.

The total amount of the organic acid catalyst and the emulsifier ispreferably 0.8 to 6 parts by mass based on 100 parts by mass oforganosiloxane. The pH of the water-based medium (A) measured at 25° C.is preferably within the range of 0.1 to 1.2, and preferably within therange of 0.5 to 1.2.

The water-based medium (A) used in the method of producing apolyorganosiloxane latex includes water, an organic acid catalyst, andan inorganic acid catalyst. Deionized water can be used for water above.The amount of water to be contained in the water-based medium (A) ispreferably 60 to 300 parts by mass, and more preferably 60 to 100 partsby mass based on 100 parts by mass of organosiloxane contained in theemulsion (B) described later. When the amount of water to be containedin the water-based medium (A) is 60 parts by mass or more, increase inthe viscosity of the latex to be obtained can be suppressed, andhandling of the latex becomes easy. When the amount of water to becontained in the water-based medium (A) is 300 parts by mass or less,production with high productivity is enabled, and reduction in theconcentration of the solid content in the latex to be obtained can besuppressed.

For the organic acid catalyst, sulfonic acids such as aliphatic sulfonicacids, aliphatic-substituted benzenesulfonic acids, andaliphatic-substituted naphthalenesulfonic acids are preferable.Aliphatic-substituted benzenesulfonic acids are more preferable becauseof their significant action to stabilize an organosiloxane latex. Analiphatic substituent for the aliphatic-substituted benzenesulfonicacids is preferably an alkyl group having 9 to 20 carbon atoms, and morepreferably an n-dodecyl group having 12 carbon atoms.

Examples of the inorganic acid catalyst include mineral acids such assulfuric acid, hydrochloric acid, and nitric acid. Among these, sulfuricacid is preferable. These may be used alone or in combination.

The amounts of these catalysts to be used are adjusted such that the pHat 25° C. of the water-based medium (A) falls within the range of 0 to1.2 because the pH of the water-based medium (A) is an important factorto determine the particle diameter of polyorganosiloxane to be obtained.By adjusting the pH of the water-based medium (A) in the above range,polyorganosiloxane having a narrow particle diameter distribution can beobtained. The pH at 25° C. of the water-based medium (A) is preferablyin the range of 0.5 to 1.2 because adjustment is easy.

The pH of the water-based medium (A) is an important factor to determinethe particle diameter of polyorganosiloxane for the following reason.Organosiloxane existing in oil droplets of the emulsion (B) contactswith the acid catalyst to form silanol. Silanol dissolves in the aqueousphase, comes to a micelle of the organic acid catalyst and theemulsifier, and condensation reaction occurs. This reaction progressessimultaneously with the condensation reaction of organosiloxane in oildroplets. When the pH of the water-based medium (A) is sufficiently low,the generation rate of silanol becomes faster, the condensation reactionby silanol is accelerated, and the rate of the condensation reaction oforganosiloxane in oil droplets becomes relatively slower. As a result,polyorganosiloxane having a narrow particle diameter distribution isformed. Meanwhile, when the pH of the water-based medium (A) is morethan 1.2, the generation rate of silanol becomes slower, and progressionof the condensation reaction of organosiloxane in oil droplets cannot beneglected. As a result, the particle diameter of polyorganosiloxane tobe obtained is larger, and the particle diameter distribution is wider.By controlling the pH of the water-based medium (A) in the above range,polyorganosiloxane having a narrow particle diameter distribution can beobtained.

Such a pH of the water-based medium (A) can be adjusted by adjusting thecontents of the organic acid catalyst and the inorganic acid catalyst.Here, the value of the pH to be used is a value obtained by measuringthe water-based medium (A) at 25° C. with a pH meter (Model PH82: madeby Yokogawa Electric Corporation) and correcting the measured value atpHs of 4.01 and 6.86 by two-point calibration.

The content of the organic acid catalyst in the water-based medium (A)is preferably 0.1 to 5.5% by mass, and more preferably 0.1 to 2.5% bymass. The content of the inorganic acid catalyst in the water-basedmedium (A) is preferably 0.5 to 2.0% by mass, and more preferably 1.3 to2.0% by mass from the viewpoint of preventing decomposition, coloring,and the like of a resin by the inorganic acid catalyst remaining in thelatex when an additive or the like for a resin is synthesized using thelatex to be obtained as a raw material. The values of these contents arebased on 100% by mass of the water-based medium (A). The water-basedmedium (A) can be obtained by properly mixing and stirring thesecomponents.

The emulsion (B) includes organosiloxane, an emulsifier, and water. Fororganosiloxane, both linear organosiloxanes and cyclic organosiloxanescan be used. Cyclic organosiloxanes are preferable because they havehigh polymerization stability and a high polymerization rate. For cyclicorganosiloxanes, those having a 3- to 7-membered ring are preferable.Examples thereof can include hexamethylcyclotrisiloxane,octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane,tetramethyltetraphenylcyclotetrasiloxane, andoctaphenylcyclotetrasiloxane. These may be used alone or in combination.

For the above organosiloxanes, commercially available products such asDMC made by Shin-Etsu Chemical Co., Ltd. can be used.

For the emulsifier used for the emulsion (B), anionic emulsifiers ornonionic emulsifiers are preferable. Examples of the anionic emulsifiersinclude sodium alkylbenzene sulfonate, sodium alkyldiphenyl etherdisulfonate, sodium alkyl sulfate, sodium polyoxyethylene alkyl sulfate,and sodium polyoxyethylene nonylphenyl ether sulfate.

Examples of the nonionic emulsifiers include polyoxyethylene alkylether, polyoxyethylene alkylene alkyl ether, polyoxyethylenedistyrenated phenyl ether, polyoxyethylene tribenzyl phenyl ether,polyoxyethylene polyoxypropylene glycol and the like. These emulsifiersmay be used alone or in combination.

The content of the emulsifier in the emulsion (B) needs to be such anamount that organosiloxane can be dispersed in fine oil droplets, thefine oil droplets can adequately contact with the organic acid catalystcontained in the water-based medium (A), and generation of silanol canbe promoted. For the content of the emulsifier, the total amount of theemulsifier and the organic acid catalyst contained in the water-basedmedium (A) is in the range of 0.5 to 6 parts by mass based on 100 partsby mass of organosiloxane. When the content of the organic acid catalystis reduced, the content of the emulsifier is competitively increased inorder to adjust the total amount of these components within the range of0.5 to 6 parts by mass. When the total amount of these components is 0.5parts by mass or more based on 100 parts by mass of organosiloxane, themass average particle diameter of the polyorganosiloxane to be obtainedcan be controlled to be 200 nm or less, and the particle diameterdistribution can be narrowed. When the total amount of these componentsis 6 parts by mass or less based on 100 parts by mass of organosiloxane,the mass average particle diameter of the polyorganosiloxane to beobtained is 100 nm or more, and the particle diameter distribution isnarrowed. The total amount of these components is preferably 0.8 to 6parts by mass, and more preferably 0.8 to 3 parts by mass based on 100parts by mass of organosiloxane.

Further, preferably, the amount of the organic acid catalyst is 0.3 to5.5 parts by mass and the amount of the emulsifier is 0.5 to 5.7 partsby mass based on 100 parts by mass of organosiloxane.

For water used for the emulsion (B), deionized water can be used. Thecontent of water in the emulsion (B) is preferably 10 times or less themass of organosiloxane. When the content of water is 10 times or lessthe mass of organosiloxane, reduction in the concentration ofpolyorganosiloxane in the latex to be obtained can be suppressed. When avinyl monomer is added to the polyorganosiloxane latex having a propervalue of the concentration of polyorganosiloxane and graftpolymerization is performed, a graft copolymer can be synthesizedefficiently by one stage polymerization. When the polyorganosiloxanelatex to be obtained is used as a coating material, increase in thedrying time of the coating film can be suppressed.

The emulsion (B) can contain a siloxane-based crosslinking agent and/ora siloxane-based grafting agent. For these crosslinking agents andgrafting agents, those having a siloxy group are preferable. By usingthe siloxane-based crosslinking agent, polyorganosiloxane having acrosslinking structure can be obtained. Examples of the siloxane-basedcrosslinking agent include trifunctional or tetrafunctional silane-basedcrosslinking agents such as trimethoxymethylsilane,triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane,tetra-n-propoxysilane, and tetrabutoxysilane. Among these,tetrafunctional crosslinking agents are preferable, andtetraethoxysilane is more preferable. The content of the crosslinkingagent is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 5parts by mass, and most preferably 0.5 to 3 parts by mass based on 100parts by mass of organosiloxane.

The siloxane-based grafting agent has a siloxy group and a functionalgroup which is polymerizable with a vinyl monomer. By using asiloxane-based grafting agent, polyorganosiloxane having a vinyl monomerand a functional group which is polymerizable with the vinyl monomer canbe obtained. For this reason, a vinyl monomer can be grafted to thepolyorganosiloxane thus obtained by radical polymerization. Examples ofthe siloxane-based grafting agent include siloxane represented byformula (I).

RSiR¹ _(n)(OR²)_((3-n))  (I)

In formula (I), R¹ represents a methyl group, an ethyl group, a propylgroup, or a phenyl group; R² represents an organic group in an alkoxygroup, and examples thereof include a methyl group, an ethyl group, apropyl group, or a phenyl group; n represents 0, 1, or 2; R represents agroup represented by formulas (I-1) to (I-4).

CH₂═C(R³)—COO—(CH₂)_(p)—  (I-1)

CH₂═C(R⁴)—C₆H₄—  (I-2)

CH₂═CH—  (I-3)

HS—(CH₂)_(p)—  (I-4)

In these formulas, R³ and R⁴ each represents hydrogen or a methyl group,and p represents an integer of 1 to 6.

Examples of the functional group represented by formula (I-1) include amethacryloyloxyalkyl group. Examples of siloxane having this groupinclude β-methacryloyloxyethyldimethoxymethylsilane,γ-methacryloyloxypropylmethoxydimethylsilane,γ-methacryloyloxypropyldimethoxymethylsilane,γ-methacryloyloxypropyltrimethoxysilane,γ-methacryloyloxypropylethoxydiethylsilane,γ-methacryloyloxypropyldiethoxymethylsilane, andδ-methacryloyloxybutyldiethoxymethylsilane.

Examples of the functional group represented by formula (I-2) include avinylphenyl group and the like. Examples of siloxane having this groupinclude vinylphenylethyldimethoxysilane.

Examples of siloxane having the functional group represented by formula(I-3) include vinyltrimethoxysilane and vinyltriethoxysilane.

Examples of the functional group represented by formula (I-4) include amercaptoalkyl group. Examples of siloxane having this group includeγ-mercaptopropyldimethyoxymethylsilane,γ-mercaptopropylmethoxydimethylsilane,γ-mercaptopropyldiethoxymethylsilane,γ-mercaptopropylethoxydimethylsilane, andγ-mercaptopropyltrimethoxysilane.

These siloxane-based grafting agents may be used alone or incombination.

The content of the siloxane-based grafting agent is preferably 0.05 to20 parts by mass based on 100 parts by mass of organosiloxane. Thesiloxane-based crosslinking agent and the siloxane-based grafting agentare preferably used in combination. 0.5 to 5 parts by mass of thesiloxane-based crosslinking agent and 0.05 to 5 parts by mass of thesiloxane-based grafting agent are preferably used in combination basedon 100 parts by mass of organosiloxane.

Further, the emulsion (B) may contain a siloxane oligomer having aterminal blocking group if necessary. The siloxane oligomer having aterminal blocking group refers to a siloxane oligomer that has an alkylgroup or the like at the terminal of the organosiloxane oligomer, andterminates polymerization of polyorganosiloxane.

Examples of the siloxane oligomer having a terminal blocking groupinclude hexamethyldisiloxane,1,3-bis(3-glycidoxypropyl)tetramethyldisiloxane,1,3-bis(3-aminopropyl)tetramethyldisiloxane, and methoxytrimethylsilane.

The emulsion (B) can be prepared by an emulsion method of mixingorganosiloxane, the emulsifier, and water described above, and stirringthe mixture such that a shear force is applied thereto. For the stirrer,typical stirring apparatuses having a stirring blade and a tank can beused. Preferably, a high pressure emulsifying apparatus can be used. Thehigh pressure emulsifying apparatus is an apparatus that stirs a rawmaterial mixture at a high pressure, and emulsifies the mixture byapplying a shear force. Examples thereof include a homogenizer. By usingsuch a high pressure emulsifying apparatus, a stable emulsion canefficiently be generated.

The thus-obtained emulsion (B) is dropped into the water-based medium(A). Thereby, a polyorganosiloxane latex can be obtained. Thetemperature of the water-based medium (A) is preferably 60 to 100° C.,and more preferably 80° C. or more. When the temperature of thewater-based medium (A) is 60° C. or more, the acid catalyst cansufficiently dissociate, and contact with organosiloxane to generatesilanol effectively. When the temperature of the water-based medium (A)is 100° C. or less, a high pressure polymerization facility isunnecessary.

When the total amount of organosiloxane to be used is 100 parts by mass,the dropping rate of the emulsion (B) is preferably a rate such that theamount of organosiloxane to be fed is 0.5 [parts by mass/min] or less,and more preferably 0.3 [parts by mass/min] or less. When the amount oforganosiloxane to be fed is 0.5 [parts by mass/min] or less, generationof silanol can be accelerated, and progression of the condensationreaction of organosiloxane in a micelle containing no acid catalyst canbe suppressed. As a result, polyorganosiloxane having a narrow particlediameter distribution is obtained.

When the total amount of organosiloxane to be used is 100 parts by mass,the dropping rate of the emulsion (B) is preferably a rate such that theamount of organosiloxane to be fed is 0.05 [parts by mass/min] or more,and more preferably 0.08 [parts by mass/min] or more. When the amount oforganosiloxane to be fed is 0.05 [parts by mass/min] or more, reductionin productivity can be suppressed.

The emulsion (B) is preferably dropped at a temperature of 60 to 100° C.for 3 to 34 hours. This operation can efficiently progress the reaction.

After dropping of the emulsion (B) is completed, further, heating ispreferably performed. Heating can be performed for 2 to 50 hours, forexample. By heating after dropping, silanol derived from organosiloxanecan almost completely be reacted.

Further, because the crosslinking reaction between silanol progresses ata temperature of 30° C. or less, the temperature of 30° C. or less canbe kept for approximately 5 to 100 hours in order to increase thecrosslinked density of polyorganosiloxane.

The condensation reaction for polyorganosiloxane can be terminated byneutralizing the latex with an alkaline substance such as sodiumhydroxide, potassium hydroxide, and an aqueous ammonia solution to a pHof 6 to 8.

The thus-obtained polyorganosiloxane has a mass average particlediameter (Dw) in the range of 100 to 200 nm and a narrow particlediameter distribution at Dw/Dn of 1.7 or less. By adjusting the totalamount of the organic acid catalyst and the emulsifier in the range of0.8 to 6 parts by mass based on 100 parts by mass of organosiloxane, themass average particle diameter of polyorganosiloxane can be adjusted tohave a desired value in the range of 100 to 200 nm.

For the particle diameter of polyorganosiloxane, a value obtained bymeasurement by the following method can be used. The polyorganosiloxanelatex is diluted with deionized water to have a concentration ofapproximately 3%, and the obtained product is used as a sample. Theparticle diameter is measured using a CHDF2000 type particle sizedistribution analyzer made by MATEC Instrument Companies, Inc., U.S.A.

The measurement can be performed on the standard condition recommendedby MATEC Instrument Companies, Inc. as below:

cartridge: dedicated capillary cartridge for separating particles (tradename; C-202),

carrier solution: dedicated carrier solution (trade name; 2XGR500),

solution properties of the carrier solution: almost neutral,

flow rate of the carrier solution: 1.4 ml/min,

pressure of the carrier solution: approximately 4,000 psi (2,600 kPa),

measurement temperature: 35° C.,

amount of the sample to be used: 0.1 ml.

Among monodisperse polystyrenes made by Duke Scientific Corporation,U.S.A. and having a known particle diameter, those having 12 differentparticle diameters in total in the range of 40 to 800 nm are used as thestandard particle diameter substance.

To improve mechanical stability, an emulsifier may be added to thepolyorganosiloxane latex obtained by the above method if necessary. Thesame anionic emulsifiers and nonionic emulsifiers as those listed aboveare preferable.

The amount of the emulsifier to be added is preferably 0.05 to 10 partsby mass based on 100 parts by mass of organosiloxane. When the amount is0.05 parts by mass or more, the mechanical stability of the latex isimproved. When the amount is 10 parts by mass or less, occurrence ofcoloring can be suppressed in the additive for a resin obtained usingthe polyorganosiloxane latex as a raw material.

The polyorganosiloxane latex according to the present invention issuitably used as a raw material for an impact strength modifier for aresin. The polyorganosiloxane latex according to the present inventionis suitable for a variety of applications such as a variety of cosmeticssuch as hair cosmetics, skin cosmetics, and make-up cosmetics; lusteringagents and surface protecting agents for automobiles, furniture, leatherproducts, and the like; surface treatment agents for improvinglubrication of weather strips and the like; fiber treatment agents forcloths, curtains, bedcloths, and the like; antifoaming agents used forwaste water treatments and production of foods.

The impact strength modifier for a resin using the polyorganosiloxanelatex according to the present invention is, in particular, usefulbecause a material having a narrow particle diameter distribution and agood balance between impact strength and the surface appearance can beprovided.

[Polyorganosiloxane-Containing Vinyl-Based Copolymer]

The polyorganosiloxane-containing vinyl-based copolymer according to thepresent invention is a copolymer obtained by polymerizing one or morevinyl-based monomers in the presence of the polyorganosiloxane latexwherein the mass average particle diameter (Dw) is 100 to 200 nm andwherein the ratio (Dw/Dn) of the mass average particle diameter (Dw) tothe number average particle diameter (Dn) is 1.0 to 1.7.

The polyorganosiloxane-containing vinyl-based copolymer (hereinafter,referred to as a “composite polymer (g)” in some cases) preferably has amass average particle diameter (Dw) of 110 nm to 800 nm, and the ratio(Dw/Dn) of the mass average particle diameter (Dw) to the number averageparticle diameter (Dn) of 1.0 to 2.0.

A vinyl-based monomer usable to obtain the composite polymer (g) is notin particular limited, and examples thereof include (meth)acrylic acidester-based monomers, aromatic vinyl monomers, and vinyl cyanidemonomers.

Examples of the (meth)acrylic acid ester-based monomers include methyl(meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl(meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl(meth)acrylate, and 2-ethylhexyl (meth)acrylate. Examples of thearomatic vinyl monomers include styrene, α-methylstyrene, vinyltoluene,and chlorostyrene. Examples of the vinyl cyanide monomers includeacrylonitrile and methacrylonitrile. These vinyl-based monomers can beused alone or in combination. Among these vinyl-based monomers, acrylicacid ester-based monomers are preferably used.

For the polymerizable component, a grafting agent and a crosslinkingagent can also be used if necessary. Examples of the grafting agent orcrosslinking agent include polyfunctional monomers such as allylmethacrylate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene,ethylene glycol diester dimethacrylate, propylene glycol diesterdimethacrylate, 1,3-butylene glycol diester dimethacrylate, 1,4-butyleneglycol diester dimethacrylate, 1,6-hexane diol diacrylic acid ester, andtriallyl trimellitate. These can be used alone or in combination.

The method of producing the composite polymer (g) is not in particularlimited. The composite polymer (g) can be produced, for example, by anemulsion polymerization method, a suspension polymerization method, or amicro-suspension polymerization method. Use of the emulsionpolymerization method is preferable. Among these, a method of emulsionpolymerizing one or more vinyl-based monomers in the presence of thepolyorganosiloxane latex to obtain a latex of the composite polymer (g)is in particular preferable.

Examples of a method of adding a vinyl-based monomer to thepolyorganosiloxane latex include a method of adding a vinyl-basedmonomer into the polyorganosiloxane latex in a lump sum or dropwise.

In production of the latex of the composite polymer (g), an emulsifiercan be added to stabilize the latex and control the average particlediameter of the composite polymer. The emulsifier is not in particularlimited, and anionic emulsifiers and nonionic emulsifiers arepreferable.

Examples of the anionic emulsifiers include a variety of carboxylic acidsalts such as sodium sarcosinate, fatty acid potassium, fatty acidsodium, dipotassium alkenyl succinate, and rosin acid soap; sulfonicacid salts such as sodium alkylbenzene sulfonate and sodiumdiphenylether disulfonate; sulfuric acid salts such as sodium alkylsulfate, sodium polyoxyethylene alkyl sulfate, and sodiumpolyoxyethylene nonylphenyl ether sulfate; and phosphoric acid saltssuch as sodium polyoxyethylene alkyl phosphate and calciumpolyoxyethylene alkyl phosphate.

Examples of the nonionic emulsifiers include polyoxyethylene alkylether, polyoxyethylene distyrenated phenyl ether, and polyoxyethylenetribenzylphenyl ether. These emulsifiers can be used alone or incombination.

By adjusting the amounts of the emulsifier and the vinyl-based monomer,a composite polymer (g) having Dw of 110 to 800 nm and Dw/Dn of 1.0 to2.0 can be produced. The amount of the emulsifier is preferably 0.1 to20 parts by mass based on 100 parts by mass of the polyorganosiloxanelatex.

Examples of the polymerization initiator used for polymerization of thevinyl-based monomer include peroxides, azo-based initiators, or redoxtype initiators in combination of an oxidizing agent with a reducingagent. Among these, the redox type initiators, in particular,combinations of redox type initiators using ferrous sulfate,ethylenediaminetetraacetic acid disodium salt, a reducing agent andperoxide are preferable.

Examples of the peroxide include organic peroxides such asdiisopropylbenzene hydroperoxide, p-menthane hydroperoxide, cumenehydroperoxide, and t-butyl hydroperoxide. These can be used alone or incombination. Examples of the reducing agent include sodium formaldehydesulfoxylate, L-ascorbic acid, fructose, dextrose, sorbose, and inositol.These can be used alone or in combination.

For the mass ratio of the polyorganosiloxane and vinyl-based polymer inthe composite polymer (g) (100% by mass), preferably, polyorganosiloxaneis 1.0 to 99.0% by mass and the vinyl-based polymer is 99.0 to 1.0% bymass. The mass ratio can be calculated from the mass ratio ofpolyorganosiloxane to the vinyl-based monomer, the grafting agent, andthe crosslinking agent used in production of the composite polymer (g).

The composite polymer (g) can be recovered as a powder from the latex ofthe composite polymer (g). The latex of the composite polymer (g) can beused as a raw material for the graft copolymer (G) described later.

When the powder of the composite polymer (g) is recovered from the latexof the composite polymer (g), one of a spray drying method and acoagulation method can be used.

The spray drying method is a method in which the latex of the compositepolymer (g) is sprayed in a dryer in a form of micro liquid droplets,and these droplets are dried by applying a heated gas for drying.Examples of a method for generating micro liquid droplets include arotary disk method, a pressure nozzle method, a two-fluid nozzle method,and a pressurized two-fluid nozzle method. The dryer may have a smallvolume for use in a laboratory, or a large volume for industrial use.The temperature of the heated gas for drying is preferably 200° C. orless, and more preferably 120 to 180° C. The latexes of two or morecomposite polymers (g) individually produced can also be spray driedtogether. Further, to improve powder properties such as blocking duringspray drying and bulk specific gravity, optional component such assilica can also be added to a polymer latex and spray drying can beperformed.

The coagulation method is a method in which the latex of the compositepolymer (g) is put into very hot water in which calcium chloride,calcium acetate, aluminum sulfate, or the like is dissolved; thecomposite polymer (g) is separated by salting-out and coagulation; next,the separated wet composite polymer (g) is dehydrated to reduce thecontent of water, and recovered; further, the recovered compositepolymer (g) is dried using a squeeze dehydrator or a hot air dryer.

Examples of a coagulant used in coagulation of the composite polymer (g)from the latex include inorganic salts such as aluminum chloride,aluminum sulfate, sodium sulfate, magnesium sulfate, sodium nitrate, andcalcium acetate and acids such as sulfuric acid. These coagulants may beused alone or in combination. When these are used in combination, acombination that does not allow formation of a water-insoluble salt isrequired. For example, if calcium acetate is used in combination withsulfuric acid or a sodium salt thereof, a water-insoluble calcium saltis formed. This combination is not preferable.

The above coagulant is usually used in a form of an aqueous solution.The concentration of the coagulant aqueous solution is 0.1% by mass ormore, and in particular preferably 1% by mass or more from the viewpointof stably coagulating and recovering the composite polymer (g). Theconcentration of the coagulant aqueous solution is 20% by mass or less,and in particular preferably 15% by mass or less from the viewpoint ofreducing the amount of the coagulant remaining in the recoveredcomposite polymer (g) and thereby suppressing coloring of the moldedarticle. The amount of the coagulant aqueous solution is not inparticular limited. The amount is 10 parts by mass or more, andpreferably 500 parts by mass or less based on 100 parts by mass of thelatex.

The method of contacting the latex with the coagulant aqueous solutionis not in particular limited. Examples thereof usually include a methodin which while the coagulant aqueous solution is stirred, the latex iscontinuously added thereto and the solution is kept for a predeterminedperiod of time, and a method in which the coagulant aqueous solution iscontacted with the latex while these materials are continuously chargedinto a container having a stirrer at a predetermined ratio; and amixture of a flocculated polymer and water is continuously extractedfrom the container. The temperature when the latex contacted with thecoagulant aqueous solution is not in particular limited. The temperatureis 30° C. or more, and preferably 100° C. or less. The time for thecontact is not in particular limited.

The flocculated composite polymer (g) is washed with water approximately1 to 100 times the mass thereof. The filtered wet composite polymer (g)is dried using a fluidized bed dryer, a squeeze dehydrator, or the like.The temperature and the time for drying may be properly determineddepending on the composite polymer (g) to be obtained. Withoutrecovering the composite polymer (g) discharged from a squeezedehydrator or an extruder, the composite polymer (g) may directly besent to an extruder or a molding machine that produces a resincomposition, and may be mixed with other thermoplastic resins to obtaina molded body.

[Graft Copolymer (G)]

A graft copolymer (G) according to the present invention is a graftcopolymer obtained by graft polymerizing one or more vinyl-basedmonomers in the presence of the polyorganosiloxane-containingvinyl-based copolymer. A composite polymer (g) according to the presentinvention can be used as a raw material for a graft copolymer (G).Examples of the graft polymerization method include a method ofpolymerizing a vinyl-based monomer (hereinafter, referred to as a“monomer for grafting” in some cases) in the presence of the latex ofthe composite polymer (g). By performing polymerization using the samemethod as that in production of the latex of the composite polymer (g)described above, the latex of the graft copolymer (G) can be obtained.

For the monomer for grafting, the same (meth)acrylic acid ester-basedmonomers, aromatic vinyl monomers, and vinyl cyanide monomers as thosedescribed in production of the composite polymer (g) are preferable.

Examples of the graft polymerization method include a method in whichthe monomer for grafting is fed into the latex of the composite polymer(g), and polymerization is performed at one or multi stages.Specifically, examples thereof include a batch polymerization method offeeding the total amount of the monomer for grafting at one time and aconsecutive polymerization method of feeding the monomer for grafting bycontinuously dropping the monomer for grafting (hereinafter, referred toas a “semi-batch polymerization method”). As an intermediate operation,a method in which the monomer for grafting is divided into portionshaving a small amount, and an operation of “feeding a small amount ofthe monomer for grafting and polymerization” is repeated at many stagescan be used. The semi-batch polymerization method is preferable becausethe stability during polymerization is high and a latex having a desiredparticle diameter and particle diameter distribution can be obtained.

Examples of the emulsifier used in graft polymerization include the sameemulsifiers as those described in production of the composite polymer(g). The anionic emulsifiers and nonionic emulsifiers are preferable.

Examples of the polymerization initiator used in the graftpolymerization include the same polymerization initiators used inproduction of the composite polymer (g). In particular, polymerizationinitiators in combination of ferrous sulfate, ethylenediaminetetraaceticacid disodium salt, a reducing agent, and peroxide are preferably used.

When powders of a graft copolymer (G) is recovered from the latex of thegraft copolymer (G), one of the spray drying method and the coagulationmethod can be used similarly in the case of recovering powders of thecomposite polymer (g).

Examples of preferable embodiments of the graft copolymer (G) accordingto the present invention include graft copolymers (Ga) and (Gb)described later. Examples of preferable embodiments of the compositepolymer (g) according to the present invention include compositepolymers (ga) and (gb) described later.

[Graft Copolymer (Ga)]

A graft copolymer (G) according to the present invention is preferably agraft copolymer (Ga), wherein a molded body obtained by molding thefollowing composition exhibits the following performance (1) and (2)when evaluated under the following measurement conditions:

(1) a Charpy impact strength at 23° C. is 6 kJ/m² or more, and

(2) a diffuse reflectance is 5% or less.

<Test Piece Production Condition>

(a) 33 parts by mass of a graft copolymer (G),

(b) 9 parts by mass of an acrylonitrile•styrene copolymer including 25%by mass of an acrylonitrile unit and 75% by mass of a styrene unit andhaving a reduced viscosity (ηsp/c) of 0.40 dL/g in anN,N-dimethylformamide solution of 0.2 g/dL at 25° C.,

(c) 9 parts by mass of an acrylonitrile-styrene copolymer including 28%by mass of an acrylonitrile unit and 72% by mass of a styrene unit andhaving a reduced viscosity of 0.62 dL/g in an N,N-dimethylformamidesolution of 0.2 g/dL at 25° C.,

(d) 50 parts by mass of an acrylonitrile-styrene-N-phenylmaleimidecopolymer including 22% by mass of an acrylonitrile unit, 55% by mass ofa styrene unit, and 23% by mass of an N-phenylmaleimide unit and havinga reduced viscosity of 0.66 dL/g in an N,N-dimethylformamide solution of0.2 g/dL at 25° C.,

(e) 0.5 parts by mass of ethylenebisstearylamide,

(f) 0.03 parts by mass of silicone oil, and

(g) 0.05 parts by mass of carbon black.

These seven materials (a) to (g) above are blended, and kneaded using avolatilizing extruder (TEX-30α made by The Japan Steel Works, Ltd.)whose barrel is heated to a temperature of 260° C. to obtain pellets.The pellets are molded using a 4-ounce injection molding machine (madeby The Japan Steel Works, Ltd.) in conditions of a cylinder temperatureof 260° C. and a mold temperature of 60° C. to obtain a test piece 1 (alength of 80 mm, a width of 10 mm and a thickness of 4 mm). Moreover, aplate-like molded body 2 (a length of 100 mm, a width of 100 mm and athickness of 2 mm) is obtained in the same manner as above in conditionsof a cylinder temperature of 260° C., a mold temperature of 60° C., andan injection rate of 5 g/sec.

<Charpy Impact Strength Measurement Condition>

Measurement is conducted on a V-notched test piece 1 that is left undera 23° C. atmosphere for 12 hours or more by a method according to ISO179.

<Diffuse Reflectance Measurement Condition>

A 50 nm aluminum film is formed (through a direct deposition) on thesurface of the molded body 2 by a vacuum deposition method (VPC-1100made by ULVAC-PHI, Inc.) in conditions of a degree of vacuum of 6.0×10⁻³Pa and a film forming rate of 10 angstroms/sec. A diffuse reflectance(%) of the obtained molded body is measured using a reflectance meter(TR-1100AD made by Tokyo Denshoku Co., Ltd.).

A composite polymer (g) according to the present invention is preferablya composite polymer (ga) which contains 5 to 25% by mass ofpolyorganosiloxane and has a mass average particle diameter (Dw) of 120to 200 nm, in which a proportion of the particle having a particlediameter of 100 nm or less is 15% by mass or less based on the totalamount of the particle, and in which a proportion of the particle havingthe particle diameter of 400 nm or more is 1% by mass or less based onthe total amount of the particle. A graft copolymer (Ga) according tothe present invention is preferably a copolymer obtained by graftpolymerizing a mixture of a vinyl cyanide-based monomer and an aromaticvinyl-based monomer with the composite polymer (ga).

A molded body obtained from the graft copolymer (Ga) preferably hasperformances as below:

(1′) A Charpy impact strength at 23° C. is 6 kJ/m² or more, and 50 kJ/m²or less, and

(2′) A diffuse reflectance is 0.1% or more, and 5% or less.

The polyorganosiloxane that forms the composite polymer (ga) preferablycontains 0.5 to 5 parts by mass of a component derived from asiloxane-based crosslinking agent based on 100 parts by mass oforganosiloxane.

The vinyl-based polymer that forms the composite polymer (ga) is anacrylic acid ester monomer, or an acrylic acid ester-based polymerobtained by polymerizing a monomer mixture containing one or moreacrylic acid ester monomers.

Examples of the acrylic acid ester-based monomers include methylacrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, and2-ethylhexyl acrylate. These can be used alone or in combination. Amongthese, n-butyl acrylate is preferable because the molded body obtainedfrom the resin composition has high impact resistance.

For the polymerizable component, a grafting agent and a crosslinkingagent can be used if necessary. For the grafting agent and thecrosslinking agent, the same polyfunctional monomers as those used inproduction of the composite polymer (g) can be used. These may be usedalone or in combination. The amount of the grafting agent andcrosslinking agent to be added may be properly determined. From theviewpoint of a good balance between the impact resistance of the moldedbody and brightness after direct deposition, the amount is preferably0.1 to 5 parts by mass, more preferably 0.2 to 2 parts by mass, and inparticular preferably 0.4 to 1.0 part by mass based on 100 parts by massof the acrylic acid ester-based monomer (including a mixture). A smalleramount is preferable from the viewpoint of impact resistance, and alarger amount is preferable from the viewpoint of brightness.

A method of producing the composite polymer (ga) is not in particularlimited. A method of mixing a polyorganosiloxane latex with an acrylicacid ester-based polymer latex and heteroaggregating or co-enlarging ofparticles in the mixture may be used, or the same method as that used inproduction of the composite polymer (g) described above may be used. Atthis time, the monomer may be a mixture. Among these, a method ofpolymerizing an acrylic acid ester-based monomer in the presence of thepolyorganosiloxane latex is preferable from the viewpoint of the impactresistance of the molded body, the brightness of the molded body afterdirect deposition and appearance of welding portion.

For the content of the acrylic acid ester-based polymer derived frompolyorganosiloxane and the acrylic acid ester-based monomer, in thecomposite polymer (ga), preferably, the content of polyorganosiloxane is5 to 25% by mass and the content of acrylic acid ester-based polymer is95 to 75% by mass from the viewpoint of high impact resistance of themolded body and remarkable brightness of the molded body after directdeposition. The content of polyorganosiloxane is more preferably 7 to20% by mass, and in particular preferably 9 to 16% by mass. As thecontent of polyorganosiloxane reduces, impact resistance tends toreduce. As the content of polyorganosiloxane increases, brightness afterdirect deposition tends to reduce.

The mass average particle diameter (Dw) of the composite polymer (ga)particle is 120 nm to 200 nm from the viewpoint of high impactresistance of the molded body and remarkable brightness of the moldedbody after direct deposition. As the mass average particle diameterreduces, impact resistance of the molded body tends to reduce. As themass average particle diameter increases, brightness of the molded bodyafter direct deposition tends to reduce.

In order to obtain a molded body having a high level brightness afterdirect deposition, the proportion of the composite polymer particlehaving a particle diameter of 100 nm or less is preferably 15% by massor less, more preferably 10% by mass or less, and still more preferably5% by mass or less, in 100% by mass of the composite polymer (ga). Fromthe viewpoint of a molded body having remarkable brightness after directdeposition, the proportion of the composite polymer particle having aparticle diameter of 400 nm or more is 1% by mass or less.

The mass average particle diameters (Dw) of a composite polymer (ga) anda graft copolymer (G) to be used are a value measured by the followingmethod. Using a Nanotrac UPA-EX150 made by NIKKISO CO., LTD., theparticle size distribution in the latex of the composite polymer (ga)and the latex of the graft copolymer (G) is measured by the dynamiclight scattering method. From the obtained particle size distribution,the mass average particle diameter, the proportion of the particlehaving a particle diameter of 100 nm or less, and the proportion of theparticle having a particle diameter of 400 nm or more are calculated.

In order to obtain a composite polymer (ga) having a mass averageparticle diameter of 120 to 200 nm and a graft copolymer (G), theparticle diameter of polyorganosiloxane may be adjusted. The massaverage particle diameter (Dw) of polyorganosiloxane is preferably 100nm to 150 nm, and Dw/Dn is preferably 1.00 to 1.70.

The monomer for grafting is not in particular limited. Examples thereofinclude the same aromatic vinyl-based monomers, (meth)acrylic acidester-based monomers, and vinyl cyanide-based monomers as those used inthe case of the composite polymer (g) described above.

Examples of the aromatic vinyl-based monomers include styrene,α-methylstyrene, and vinyltoluene. Examples of the (meth)acrylic acidester-based monomers include methyl methacrylate, ethyl methacrylate,2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, and butylacrylate. Examples of the vinyl cyanide-based monomers includeacrylonitrile and methacrylonitrile. These vinyl-based monomers can beused alone or in combination. Among these, use of the aromaticvinyl-based monomer in combination with the vinyl cyanide-based monomeris preferable, and use of styrene in combination with acrylonitrile isin particular preferable from the viewpoint of high impact resistance ofthe molded body.

When an aromatic vinyl compound is used in combination with a vinylcyanide compound, preferably 20 to 40% by mass of the vinylcyanide-based monomer and 80 to 60% by mass of the aromatic vinyl-basedmonomer are contained, and more preferably 25 to 35% by mass of thevinyl cyanide-based monomer and 75 to 65% by mass of the aromaticvinyl-based monomer are contained, in 100% by mass of a monomer mixturefor grafting. As the content of the vinyl cyanide-based monomer reduces,impact resistance tends to reduce. As the content increases, fluiditytends to reduce.

The mass ratio of a composite polymer (ga) to a monomer mixture forgrafting as raw materials is not in particular limited. From theviewpoint of high impact resistance of the molded body, high fluidity,and remarkable brightness after direct deposition, preferably the ratioof the composite polymer (ga) is 20 to 80% by mass and the ratio of themonomer for grafting is 80 to 20% by mass, and in particular preferablythe ratio of the composite polymer (ga) is 40 to 70% by mass and theratio of the monomer for grafting is 60 to 30% by mass. As the contentof the composite polymer (ga) reduces, impact resistance tends toreduce. As the content of the composite polymer (ga) increases,brightness after direct deposition tends to reduce.

Examples of the graft polymerization method include the same method asthose used in production of the composite polymer (ga) described above.Among these, emulsion polymerization is suitable. Examples of theemulsifier include the same as those used in production of the compositepolymer (ga) described above. The following are preferable from theviewpoint of high stability of the latex during emulsion polymerizationand increase in the polymerization rate: a variety of carboxylic acidsalts such as sodium sarcosinate, fatty acid potassium, fatty acidsodium, dipotassium alkenyl succinate, and rosin acid soap; and anionicemulsifiers such as alkyl sulfuric acid ester, sodium alkylbenzenesulfonate, and sodium dodecyldiphenyl ether disulfonate. These are usedaccording to the purpose. Without using an emulsifier during graftpolymerization, the emulsifier used in production of polyorganosiloxaneor the composite polymer (ga) can be used as it is.

The emulsifiers listed here are also suitable for polymerization of theacrylic acid ester-based polymer that forms the composite polymer (ga).

Examples of the radical polymerization initiator used in graftpolymerization include the same as the polymerization initiators used inproduction of the composite polymer (ga) described above. In particular,use of ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, areducing agent and peroxide in combination is preferable. The radicalpolymerization initiators listed are also suitable in polymerization forthe acrylic acid ester-based polymer that forms the composite polymer(ga).

In order to control the graft rate and the molecular weight of the graftcomponent, for example, a variety of chain transfer agents such asmercaptan-based compounds, terpene-based compounds, and α-methylstyrenedimers can be used. The polymerization condition is not in particularlimited, and can properly be set if necessary.

When powders of a graft copolymer (Ga) is recovered from the latex ofthe graft copolymer (Ga), one of the spray drying method and thecoagulation method can be used similarly in the case of recovering thepowder of the composite polymer (ga) above. Use of the coagulationmethod is preferable.

A graft copolymer (Ga) according to the present invention can be usedfor a thermoplastic resin composition (Ia) by mixing the graft copolymer(Ga) with a thermoplastic resin (Ha) except for the graft copolymer(Ga).

[Thermoplastic Resin Composition (Ha)]

A thermoplastic resin (Ha) is not in particular limited, and examplesthereof include the following: acrylic (Ac) resins such as PMMA resins;styrene-based resins such as polystyrene (PSt), acrylonitrile-styrenecopolymers (AS resins), acrylonitrile-α-methylstyrene copolymers (α-SANresins), styrene-maleic anhydride copolymers,acrylonitrile-styrene-N-substituted maleimide ternary copolymers,acrylonitrile-styrene-α-methylstyrene-N-substituted maleimide quaternarycopolymers, styrene-maleic anhydride-N-substituted maleimide ternarycopolymers, methyl methacrylate-styrene copolymers (MS resins), andacrylonitrile-styrene-methyl methacrylate copolymers; PC resins;polyester-based resins such as polybutylene terephthalate (PBT resins),polyethylene terephthalate (PET resins), and polyethylene naphthalate(PEN resins); polyvinyl chloride; modified polyphenylene ether (modifiedPPE resins); and polyamides.

The following can also be used: polyolefins such as polyethylene andpolypropylene; styrene-based elastomers such asstyrene-butadiene-styrene (SBS), styrene-butadiene (SBR), hydrogenatedSBS, and styrene-isoprene-styrene (SIS); a variety of olefin-basedelastomers; a variety of polyester-based elastomers; polyacetal resins;ethylene-vinyl acetate copolymers; PPS resins; PES resins; PEEK resins;polyarylate; and liquid crystal polyester resins.

These thermoplastic resins (Ha) can be used alone or in combination.Among these, styrene-based resins are preferable, AS resins, α-SANresins, and copolymers made from vinyl cyanide-based monomer, aromaticvinyl-based monomer and N-substituted maleimide are more preferablyused, and styrene-based resins including a copolymer including 0 to 40%by mass of a vinyl cyanide-based monomer unit, 40 to 80% by mass of anaromatic vinyl-based monomer unit, and 0 to 60% by mass of anothermonomer unit whose monomer is copolymerizable with these monomers, suchas N-substituted maleimide, are still more preferable from the viewpointof remarkable brightness after direct deposition, high impactresistance, high heat plate welding properties, and high vibrationwelding properties of the molded body produced from the thermoplasticresin composition (Ia). For the vinyl cyanide-based monomer,acrylonitrile is preferable. For the aromatic vinyl-based monomer,styrene and/or α-methylstyrene is preferable.

When an AS resin or α-SAN resin is used, the composition in particularpreferably includes 20 to 35% by mass of the vinyl cyanide-based monomerunit, and 65 to 80% by mass of the aromatic vinyl-based monomer unit.Examples of copolymers made from vinyl cyanide-based monomer, aromaticvinyl-based monomer and N-substituted maleimide includeacrylonitrile-styrene-N-substituted maleimide ternary copolymers andacrylonitrile-styrene-α-methylstyrene-N-substituted maleimide quaternarycopolymers. When these copolymers made from vinyl cyanide-based monomer,aromatic vinyl-based monomer and N-substituted maleimide are used, thecomposition of the copolymers in particular preferably includes 0 to 35%by mass of a vinyl cyanide-based monomer unit, 40 to 70% by mass of anaromatic vinyl-based monomer unit, and 5 to 60% by mass of anN-substituted maleimide unit. For the vinyl cyanide-based monomer,acrylonitrile is preferable. For the aromatic vinyl-based monomer,styrene and/or α-methylstyrene is preferable.

[Thermoplastic Resin Composition (Ia)]

A thermoplastic resin composition (Ia) according to the presentinvention is a composition having a graft copolymer (Ga) and athermoplastic resin (Ha) blended. For the content in the thermoplasticresin composition (Ia), preferably, the content of the graft copolymer(Ga) is 10 to 50% by mass and the content of the thermoplastic resin(Ha) is 90 to 50% by mass. More preferably, the content of the graftcopolymer (Ga) is 20 to 45% by mass and the content of the thermoplasticresin (Ha) is 80 to 55% by mass. By blending the graft copolymer (Ga)with the thermoplastic resin (Ha) at such mass ratio, the molded bodyhas remarkable brightness after direct deposition, high impactresistance, high heat plate welding properties, and high vibrationwelding properties. As the content of the graft copolymer (Ga) reduces,impact resistance and heat plate welding properties tend to reduce. Asthe content of the graft copolymer (Ga) increases, brightness afterdirect deposition and vibration welding properties tend to reduce.

In addition to the graft copolymer (Ga) and the thermoplastic resin(Ha), additives such as dyes, pigments, a stabilizer, a reinforcingagent, a filler, a flame retardant, a foaming agent, a lubricant, aplasticizer, an antistatic agent, a weather proofing agent, and a UVabsorber can be blended with the thermoplastic resin composition (Ia) ifnecessary.

The method of preparing the thermoplastic resin composition (Ia) is notin particular limited. Using a V type blender, a Henschel mixer, or thelike, the graft copolymer (Ga), the thermoplastic resin (Ha), and avariety of additives to be used if necessary, are mixed and dispersed.The mixture is melt kneaded using a kneader such as an extruder, aBanbury mixer, a pressure kneader, and a roll. Thus, the thermoplasticresin composition (Ia) can be prepared.

[Molded Body]

By molding the thermoplastic resin composition (Ia), a variety of moldedbodies are obtained. Examples of the molded body include the following:vehicle parts, in particular a variety of exterior parts and interiorparts such as front grilles used with no paint; construction materialparts such as wall materials and window frames; eating utensils; toys;home appliance parts such as housings of vacuum cleaners, housings oftelevisions, and housings of air conditioners; interior members, shipmembers, and housings of electrical apparatuses such as housings ofcommunication apparatuses, housings of notebook type personal computers,housings of mobile terminals, and housings of liquid crystal projectors.Among these, a suitable molded body is obtained by the thermoplasticresin composition (Ia) in the vehicle parts, in particular, lamphousings, obtained by performing metallization treatment on the surfaceof the molded body by the direct deposition method.

The molding method is not in particular limited. Known various moldingmethods such as an injection molding method, an extrusion moldingmethod, a blow molding method, a compression molding method, a calendermolding method, and an inflation molding can be used. Among these, inparticular, the injection molding method is preferable.

The surface of the molded body according to the present inventionsubjected to a primary process by the above variety of molding methodscan be subjected to metallization treatment by a direct depositionmethod. Namely, without performing a special pre-treatment such asformation of an undercoat treatment layer, a metallic layer of aluminum,chromium, or the like can be formed directly on the surface of themolded body by a vacuum deposition method or a sputtering method. Thebright surface subjected to metallization treatment may be left as itis. Further, to protect the surface against scratches caused by dust orthe like, the surface can be subjected to a top coat treatment to form asilicon-based coating film or the like.

According to the thermoplastic resin composition of the presentinvention, by using the above configuration, a molded body having highmechanical strength such as impact resistance and weatherability,exhibiting a remarkable beautiful bright appearance after directdeposition, and having high heat plate welding properties fortransparent resins and vibration welding properties is obtained.

[Lamp Housing for Vehicle Lighting]

A lamp housing for vehicle lighting is an integrally formed productwhich is obtained by bonding a molded body according to the presentinvention to a resin lens made of a transparent resin such as PMMAresins and PC resins by a method such as a heat plate welding method, avibration welding method, and a laser welding method. The surface of themolded body can be subjected to metallization treatment by a directdeposition method. A necessary member is optionally mounted on themolded body. The lamp housing has high mechanical strength such asimpact resistance and weatherability, and a good appearance. The lamphousing according to the present invention can be suitably used forautomobiles and the like.

Next, an example of a preferable aspect of the graft copolymer (G)according to the present invention, that is, a graft copolymer (Gb) andan example of a preferable aspect of the composite polymer (g) accordingto the present invention, that is, a composite polymer (gb) will bedescribed.

[Graft Copolymer (Gb)]

A graft copolymer (G) according to the present invention is preferably agraft copolymer (Gb), wherein a molded body obtained by molding thefollowing composition exhibits the following performance (1) and (2)when evaluated under the following measurement conditions:

(1) L* is 24 or less, and

(2) a Charpy impact strength at −30° C. is 6 kJ/m² or more.

<Test Piece Production Condition>

(a) 42 Parts by mass of a graft copolymer (Gb),

(b) 58 parts by mass of an acrylonitrile-styrene copolymer including 34%by mass of an acrylonitrile unit and 66% by mass of a styrene unit andhaving a reduced viscosity (ηsp/c) of 0.62 dL/g in anN,N-dimethylformamide solution of 0.2 g/dL at 25° C.,

(c) 0.3 parts by mass of ethylenebisstearylamide, and

(d) 0.5 parts by mass of carbon black.

These four materials (a) to (d) above are blended, and kneaded using avolatilizing extruder (made by Ikegai Corp., PCM-30) whose barrel isheated to a temperature of 230° C. to obtain pellets. The pellets aremolded using a 4-ounce injection molding machine (made by The JapanSteel Works, Ltd.) in conditions of a cylinder temperature of 230° C.and a mold temperature of 60° C. to obtain a test piece 3 (a length of80 mm, a width of 10 mm and a thickness of 4 mm) and a tensile testpiece 4 (a length of 170 mm, a width of 20 mm, a thickness of 4 mm, anda width of a tensile test portion of 10 mm).

<Charpy Impact Strength Measurement Condition>

Measurement is conducted on a V-notched test piece 3 that is left undera −30° C. atmosphere for 12 hours or more by a method according to ISO179.

<L* Measurement Condition>

L* is measured for the tensile test piece 4 using a spectrophotometerCM-508D made by Konica Minolta Sensing, Inc. on a side opposite to agate.

A composite polymer (g) according to the present invention is preferablya composite polymer (gb) which contains 15 to 80% by mass ofpolyorganosiloxane, and has a mass average particle diameter of 110 to250 nm, in which a proportion of the particle having a particle diameterless than 100 nm is 20% by mass or less based on the total amount of theparticle, and in which a proportion of the composite polymer particlehaving a particle diameter of 300 nm or more is 20% by mass or lessbased on the total amount of the particle. A graft copolymer (Gb)according to the present invention is preferably a copolymer obtained bygraft polymerizing a mixture of a vinyl cyanide-based monomer and anaromatic vinyl-based monomer with the composite polymer (gb).

The molded body obtained from the graft copolymer (Gb) preferably hasperformances as below:

(1′) L* is 1 or more and 24 or less, and

(2′) a Charpy impact strength at −30° C. is 6 kJ/m² or more and 30 kJ/m²or less.

The polyorganosiloxane that forms the composite polymer (gb) preferablycontains 0.5 to 3 parts by mass of the component derived from asiloxane-based crosslinking agent based on 100 parts by mass oforganosiloxane.

The vinyl-based polymer that forms the composite polymer (gb) is anacrylic acid ester-based polymer obtained by polymerizing an acrylicacid ester monomer or a monomer mixture containing one or more acrylicacid ester monomers.

Examples of the acrylic acid ester-based monomers include the same asthose used in production of the composite polymer (ga). These can beused alone or in combination. Among these, n-butyl acrylate ispreferable because the resin composition to be obtained has high impactresistance.

In the vinyl-based monomer that forms the composite polymer (gb), agrafting agent and a crosslinking agent can be used if necessary. Forthe grafting agent and the crosslinking agent, the same polyfunctionalmonomers as those used in production of the composite polymer (ga) canbe used. These may be used alone or in combination. The amount of thepolyfunctional monomer to be used is preferably 0.1 to 5 parts by mass,more preferably 0.2 to 2 parts by mass, and most preferably 0.4 to 1.0part by mass based on 100 parts by mass of the acrylic acid ester-basedmonomer. A smaller amount is preferable from the viewpoint of the impactresistance of the molded body. A larger amount is preferable from theviewpoint of an appearance of the surface of the molded body.

For the method of producing the composite polymer (gb), the same methodsas those used in production of the composite polymer (ga) can be used.

For the content ratio of polyorganosiloxane to the acrylic acidester-based polymer derived from the acrylic acid ester-based monomer inthe composite polymer (gb), preferably the content of polyorganosiloxaneis 15 to 80% by mass and the content of the acrylic acid ester-basedpolymer is 85 to 20% by mass, and more preferably the content ofpolyorganosiloxane is 20 to 70% by mass and the content of the acrylicacid ester-based polymer is 80 to 30% by mass from the viewpoint of highimpact resistance of the resin composition to be obtained, a goodappearance of the surface of the molded body, and high pigment coloringproperties of the molded body. As the content of polyorganosiloxanereduces, impact resistance tends to reduce. As the content ofpolyorganosiloxane increases, the appearance of the surface of themolded body and pigment coloring properties tend to reduce.

The mass average particle diameter of the composite polymer (gb) ispreferably 110 to 250 nm, and more preferably 110 to 200 nm from theviewpoint of high impact resistance of the molded body, a goodappearance of the surface, and high pigment coloring properties. As themass average particle diameter reduces, impact resistance of the moldedbody tends to reduce. As the mass average particle diameter increases,the appearance of the surface of the molded body and pigment coloringproperties tend to reduce.

In the composite polymer (gb), the proportion of the particle having aparticle diameter less than 100 nm is preferably 20% by mass or less,and more preferably 10% by mass or less based on the total amount of theparticle. The proportion of the particle having a particle diameter of300 nm or more is preferably 20% by mass or less, and more preferably10% by mass or less based on the total amount of the particle. When theproportion of the particle having a particle diameter less than 100 nmis excessively large, the impact resistance of the molded body tends toreduce. When the proportion of the particle having a particle diameterof 300 nm or more is 20% by mass or less, the molded body has a goodbalance between impact resistance and the appearance of the surfacethereof.

The mass average particle diameter of the composite polymer (gb) to beused is a value measured by the same method as that in the case of thecomposite polymer (ga).

In order to obtain a composite polymer (gb) having a mass averageparticle diameter of 110 to 250 nm, the particle diameter ofpolyorganosiloxane and the amount of the vinyl-based monomer may beadjusted. Preferably, the mass average particle diameter ofpolyorganosiloxane is 100 nm to 200 nm, and Dw/Dn is 1.00 to 1.70.

Examples of the monomer for grafting include the same as those used inproduction of the graft copolymer (Ga) described above. A monomermixture of an aromatic vinyl-based monomer and a vinyl cyanide-basedmonomer is preferable because the molded body to be obtained has highimpact resistance. In particular, a mixture of styrene and acrylonitrileis preferable. Moreover, “other monomers” can be used if necessary forthe vinyl-based monomer for grafting.

The “other monomers” are monomers copolymerizable with aromaticvinyl-based monomers, vinyl cyanide-based monomers, and (meth)acrylicacid ester-based monomers excluding the aromatic vinyl-based monomers,the vinyl cyanide-based monomer, and the (meth)acrylic acid ester-basedmonomers. Examples of the other monomers include acrylamide,methacrylamide, maleic anhydride, and N-substituted maleimide. These maybe used alone or in combination. The proportion of the “other monomers”in 100% by mass of the monomer mixture for grafting is preferably 50% bymass or less, more preferably 40% by mass or less, and most preferably20% by mass or less. If the proportion of the other monomers is theupper limit or less, impact resistance of the molded body and theappearance of the surface are well balanced.

The mass ratio of the composite polymer (gb) as raw materials to themonomer for grafting is not in particular limited. Preferably, the ratioof the composite polymer (gb) is 5 to 95% by mass and the ratio of themonomer for grafting is 95 to 5% by mass, more preferably the ratio ofthe composite polymer (gb) is 10 to 90% by mass and the ratio of themonomer for grafting is 90 to 10% by mass, and most preferably the ratioof the composite polymer (gb) is 30 to 70% by mass and the monomer forgrafting is 70 to 30% by mass. As the content of the monomer forgrafting reduces, the appearance of the surface of the molded body andpigment coloring properties tend to reduce. As the content increases,impact strength of the molded body tends to reduce.

The graft copolymer (Gb) is preferably produced by emulsion polymerizingthe monomer mixture as above in the presence of the composite polymer(gb) latex. Examples of the method of polymerizing the graft copolymer(Gb) include the same method as that used in production of the graftcopolymer (Ga) described above. Among these, emulsion polymerization issuitable. The same emulsifier as that used in production of the graftcopolymer (Ga) described above can be used.

Examples of the polymerization initiator used in graft polymerizationinclude the same polymerization initiators as those used in productionof the graft copolymer (Ga) described above. In particular, use offerrous sulfate, ethylenediaminetetraacetic acid disodium salt, areducing agent and peroxide in combination is preferable.

When powders of a graft copolymer (Gb) is recovered from the latex ofthe graft copolymer (Gb), the same methods as those used in productionof the powder of the graft copolymer (Ga) described above can be used.One of the spray drying method and the coagulation method can be used.The coagulation method is preferable.

A graft copolymer (Gb) according to the present invention can be usedfor a thermoplastic resin composition (Ib) by mixing the graft copolymer(Gb) with a thermoplastic resin (Hb) except for the graft copolymer(Gb).

[Thermoplastic Resin (Hb)]

The thermoplastic resin (Hb) is not in particular limited, and the sameresin as the thermoplastic resin (Ha) can be used. Among these, MSresins and PMMA resins are preferable for improvement in theweatherability of the molded body, PC resins are preferable forimprovement in the impact resistance of the molded body, and PBT resinsare preferable for improvement in the resistance against chemicals ofthe molded body. For improvement in the moldability of the thermoplasticresin composition, PET resins and styrene-based resins are preferable.Modified PPE resins and polyamides are preferable for improvement in theheat resistance of the molded body. Styrene-based resins are inparticular preferable for a balance between the impact resistance andmolding properties of the molded body. These thermoplastic resins (Hb)can be used alone or in combination.

The styrene-based resin is a resin including an aromatic vinyl-basedmonomer as an essential component and obtained by copolymerizing thearomatic vinyl-based monomer, if necessary, with other monomers such asa vinyl cyanide-based monomer such as vinyl cyanide, unsaturatedcarboxylic acid anhydrides, and N-substituted maleimide based monomers.These monomers may be used alone or in combination.

The styrene-based resin is preferably a resin including 0 to 40% by massof a vinyl cyanide-based monomer unit, 40 to 80% by mass of an aromaticvinyl-based monomer unit, and 0 to 60% by mass of another monomer unitwhose monomer is copolymerizable with these monomers. Specifically, ASresins, α-SAN resins, and copolymers made from vinyl cyanide-basedmonomer, aromatic vinyl-based monomer and N-substituted phenylmaleimideare in particular preferable. For the vinyl cyanide-based monomer,acrylonitrile is preferable. For the aromatic vinyl-based monomer,styrene and/or α-methylstyrene is preferable.

When an AS resin or α-SAN resin is used, the composition of the polymerincludes preferably 20 to 40% by mass of a vinyl cyanide-based monomerunit and 60 to 80% by mass of an aromatic vinyl-based monomer unit, andin particular preferably 25 to 35% by mass of a vinyl cyanide-basedmonomer unit and 65 to 75% by mass of an aromatic vinyl-based monomerunit. For the vinyl cyanide-based monomer, acrylonitrile is preferable.For the aromatic vinyl-based monomer, styrene and/or α-methylstyrene ispreferable. Examples of the copolymers made from vinyl cyanide-basedmonomer, aromatic vinyl-based monomer and N-substituted phenylmaleimideinclude acrylonitrile-styrene-N-substituted phenylmaleimide ternarycopolymers or acrylonitrile-styrene-α-methylstyrene-N-substitutedphenylmaleimide quaternary copolymer. When the copolymer made from vinylcyanide-based monomer, aromatic vinyl-based monomer and N-substitutedphenylmaleimide is used, the composition of the polymer preferablyincludes 0 to 35% by mass of a vinyl cyanide-based monomer unit, 40 to70% by mass of an aromatic vinyl-based monomer unit, and 5 to 60% bymass of an N-phenylmaleimide monomer unit.

If the proportion of the aromatic vinyl-based monomer unit contained inthe styrene-based resin is the lower limit or more, the thermoplasticresin composition has high molding properties. If the proportion of thearomatic vinyl-based monomer unit is the upper limit or less, the moldedarticle has high impact resistance. If the proportion of the vinylcyanide-based monomer unit contained in the styrene-based resin is lessthan the upper limit, coloring of the molded body caused by heat can besuppressed. If the proportion of the vinyl cyanide-based monomer unit isthe lower limit or more, the molded body has high impact resistance.

[Thermoplastic Resin Composition (Ib)]

The thermoplastic resin composition (Ib) according to the presentinvention is a composition comprising a blend of the graft copolymer(Gb) and the thermoplastic resin (Hb) except for the graft copolymer(Gb). The amount of the composite polymer (gb) existing in thethermoplastic resin composition (Ib) is preferably 5 to 50% by mass,more preferably 10 to 40% by mass, and most preferably 15 to 30% bymass. when the content of the composite polymer (gb) is 10% by mass ormore, the molded body obtained from the thermoplastic resin compositionhas high impact resistance. when the content of the composite polymercomponent is 40% by mass or less, the molded body can maintain a goodappearance and fluidity.

The thermoplastic resin composition (Ib) according to the presentinvention may contain a colorant such as pigments and dyes, a heatstabilizer, a light stabilizer, a reinforcing agent, a filler, a flameretardant, a foaming agent, a lubricant, a plasticizer, an antistaticagent, a treatment aid, and the like if necessary.

[Method of Producing Thermoplastic Resin Composition]

The thermoplastic resin composition (Ib) according to the presentinvention can be produced by the same method as that used in productionof the thermoplastic resin composition (Ia) described above.

[Molded Body]

The molded body obtained by molding the thermoplastic resin composition(Ib) according to the present invention has a good balance betweenimpact resistance, in particular impact resistance under a lowtemperature, rigidity, and the appearance of the surface, and has highweatherability. For this reason, the molded body is suitably used inapplications of automobile materials, construction materials, and homeappliances used these days. The molded article formed of thethermoplastic resin composition (Ib) can be used in variousapplications. Examples of the molded body include the same molded bodiesas those obtained by molding the thermoplastic resin composition (Ia).

Examples of the method of molding a molded body include the same methodsas those used in the case of the thermoplastic resin composition (Ia)such as an injection molding method, an extrusion molding method, a blowmolding method, a compression molding method, a calender molding method,and an inflation molding method. A post treatment such as metallizationtreatment can be performed on the molded body.

EXAMPLES

Hereinafter, the present invention will be specifically described.Hereinafter, “parts” designate “parts by mass,” and “%” designates “% bymass.” A variety of physical properties shown in Examples were evaluatedby the methods shown below.

[1. Solid Content]

The polyorganosiloxane latex was dried with a hot air dryer at 180° C.for 30 minutes, and the solid content was calculated using the followingformula.

solid content [%]=(mass of residue after drying at 180° C. for 30minutes)/(mass of latex before drying)×100

[2. Reduced Viscosity]

Using an N,N-dimethylformamide solution of the thermoplastic resin Ha orHb having a concentration of 0.2 [g/dL], the reduced viscosity of thethermoplastic resin was measured at 25° C. with an Ubbelohde viscometer.

[3. Melt Volume Rate (MVR)]

The melt volume rate of the thermoplastic resin composition Ia or Ib wasmeasured in conditions of a barrel temperature of 220° C. and a load of98 N by the method according to ISO 1133. The melt volume rate is anindex indicating the fluidity of a thermoplastic resin composition.

[4. Charpy Impact Strength]

The Charpy impact strength was measured in conditions described in thesection regarding the graft copolymer (Ga) and the graft copolymer (Gb).

[5. Flexural Modulus, Bending Strength]

The bending strength and flexural modulus of the thermoplastic resincomposition Ia or Ib was measured at the measurement temperature of 23°C. and the thickness of a test piece of 4 mm by a method according tothe ISO test method 178.

[6. Deflection Temperature Under Load]

The deflection temperature under load of the thermoplastic resincomposition Ia or Ib was measured at 1.80 MPa and the thickness of atest piece of 4 mm by a flat-wise method according to the ISO testmethod 75.

[7. Diffuse Reflectance (Brightness)]

The diffuse reflectance (%) was measured on the condition described inthe section concerned with the graft copolymer (Ga), and brightness wasevaluated. A lower value of the diffuse reflectance indicates a brightersurface of the molded article.

[8. Vibration Welding Properties]

A flat plate molded article having a thickness of 2 mm obtained byinjection molding (trapezoidal shape, width of 70 mm, short side of 110mm, and long side of 160 mm) was used. As a lens for evaluation, asample obtained by molding a PMMA resin (ACRYPET VH4 made by MITSUBISHIRAYON CO., LTD.) by injection molding into a 3 mm sheet with a rib(trapezoidal shape, width of 70 mm, short side of 110 mm, and long sideof 160 mm; rib: height of 10 mm, short side of 100 mm, and long side of150 mm) was used.

Vibration welding was performed using a BRANSON VIBRATION WELDER 2407made by Emerson Japan, Ltd. in conditions of an amplitude of 1 mm, apressure of 0.3 MPa, and a sink amount of 1.5 mm. Next, the appearanceof the melt portion produced by melting and bonding during vibrationwelding was visually observed, and evaluated according to 4 ranks asbelow:

Rank 1: welding fall properties and fluffing properties are very good inall the peripheries of the welding portion.

Rank 2: welding fall properties and fluffing properties are inferior inthe range of 0 to less than 10% of all the peripheries of the weldingportion.

Rank 3: welding fall properties and fluffing properties are inferior inthe range of 10 to less than 40% of all the peripheries of the weldingportion.

Rank 4: welding fall properties and fluffing properties are inferior inthe range of 40% or more of all the peripheries of the welding portion.

In the evaluation criterion, “welding fall properties” means that themelt portion of the sheet and the rib continues smoothly as theappearance of the bonding portion, and “fluffing properties” means theextent of fluffing produced in the melt portion. Vibration weldingproperties are excellent when these properties are good.

[9. Color Developability]

“L*” was measured in conditions described in the section concerned withthe graft copolymer (Gb). L* having a smaller numeric value indicateshigher color developability.

Example 1 Production of Polyorganosiloxane Latex (L-1)

97.5 Parts of a cyclic organosiloxane mixture (a mixture of a trimer: 5%by mass, a tetramer: 85% by mass, a pentamer: 3%, a hexamer: 6% by mass,and a heptamer: 1% by mass, made by Shin-Etsu Chemical Co., Ltd.,product name: DMC), 2 parts of tetraethoxysilane (TEOS), and 0.5 partsof γ-methacryloyloxypropyldimethoxymethylsilane (DSMA) were mixed toobtain 100 parts of an organosiloxane mixture. A solution prepared bydissolving 0.68 parts of sodium dodecylbenzenesulfonate (DBSNa) in 300parts of deionized water was added to the organosiloxane mixture, andstirred with a homomixer at 10,000 rpm for 2 minutes. Then, the solutionwas passed through a homogenizer at a pressure of 20 MPa twice to obtaina stable pre-mixed emulsion (B-1).

Meanwhile, 1 part of dodecylbenzenesulfonic acid (DBSH), 1.38 parts ofsulfuric acid, and 90 parts of deionized water were injected into aseparable flask equipped with a cooling condenser, and a water-basedmedium (A-1) at a pH of 0.84 was prepared at 25° C.

The water-based medium (A-1) was heated to 90° C. In this state, theemulsion (B-1) was dropped into the water-based medium (A-1) at a ratesuch that the amount of organosiloxane to be fed was 0.42 parts/min(substantially for 4 hours). After dropping was completed, thetemperature was kept for 2 hours, and then lowered. Next, the reactionproduct was kept at room temperature for 12 hours, and neutralized to apH of 7.0 with a 10% sodium hydroxide aqueous solution to obtain apolyorganosiloxane latex (L-1).

The solid content and particle diameter of the obtainedpolyorganosiloxane latex (L-1) were measured by the methods above. Theresults are shown in Table 3.

Examples 2 to 23, Comparative Examples 1 and 2, Reference Examples 3 to5, and Comparative Examples 6 to 8 Production of PolyorganosiloxaneLatexes (L-2 to L-30)

Polyorganosiloxane latexes (L-2 to L-30) were obtained in the samemanner as in Example 1 except that the compositions of the water-basedmedium (A) and the emulsion (B), and the dropping rate of the emulsion(B) in Example 1 were changed as the condition shown in Table 1 or Table2. Regarding the obtained polyorganosiloxane latexes, the particlediameter and the solid content were measured in the same manner as inExample 1. The results are shown in Table 3.

Comparative Example 9 Production of Polyorganosiloxane Latex (L-31)

97.5 parts of DMC, 2 parts of TEOS, and 0.5 parts of DSMA were mixed toobtain 100 parts of an organosiloxane mixture. A solution prepared bydissolving 0.68 parts of DBSNa and 0.68 parts of DBSH in 200 parts ofdeionized water was added to the organosiloxane mixture, and stirredwith a homomixer at 10,000 rpm for 2 minutes. Then, the solution waspassed through a homogenizer at a pressure of 20 MPa twice to obtain astable pre-mixed emulsion (B).

The emulsion (B) was charged into a separable flask equipped with acooling condenser, and kept at 85° C. for 6 hours to produce apolyorganosiloxane latex by polymerization. Next, the obtained reactionproduct was kept at room temperature for 12 hours, and neutralized witha 10% sodium hydroxide aqueous solution to a pH of 7.0. The particlediameter and solid content of the obtained polyorganosiloxane in thelatex were measured. The results are shown in Table 3.

TABLE 1 total amount water-based medium (A) of the organic organic acidinorganic emulsion (B) acid catalyst polyorgano- deionized catalyst acidcatalyst deionized emulsifier mixture of organosiloxane and the siloxanewater DBSH sulfuric acid water amount composition [part] feed rateemulsifier latex [part] [part] [part] pH [part] kind [part]DMC/DSMA/TEOS [part/min] [part] Example 1 L-1 90 1 1.38 0.84 300 DBSNa0.68 97.5/0.5/2 0.42 1.68 Example 2 L-2 90 1 1.38 0.84 300 DBSNa 0.6897.5/0.5/2 0.21 1.68 Example 3 L-3 90 5 0.83 0.85 300 DBSNa 0.6897.5/0.5/2 0.21 5.68 Example 4 L-4 90 3 1.19 0.83 300 DBSNa 0.6897.5/0.5/2 0.21 3.68 Example 5 L-5 90 2 1.29 0.81 300 DBSNa 0.6897.5/0.5/2 0.21 2.68 Example 6 L-6 90 0.5 1.40 0.81 300 DBSNa 0.6897.5/0.5/2 0.21 1.18 Example 7 L-7 90 0.5 1.40 0.81 300 DBSNa 297.5/0.5/2 0.21 2.50 Example 8 L-8 90 0.5 1.40 0.81 300 DBSNa 197.5/0.5/2 0.21 1.50 Example 9 L-9 90 0.4 1.58 0.82 300 DBSNa 0.6897.5/0.5/2 0.11 1.08 Example 10 L-10 90 0.3 1.57 0.77 300 DBSNa 0.6897.5/0.5/2 0.11 0.98 Example 11 L-11 90 1 1.38 0.84 300 A500 197.5/0.5/2 0.21 2.00 Example 12 L-12 90 2 1.29 0.84 300 DBSNa 0.6896/2/2 0.21 2.68 Example 13 L-13 90 2 1.29 0.79 300 DBSNa 0.68 97/2/10.21 2.68 Example 14 L-14 90 5 0.83 0.85 300 DBSNa 0.68 98/2/0 0.21 5.68Example 15 L-15 90 5 0.83 0.85 300 DBSNa 0.68 97/2/1 0.21 5.68 Example16 L-16 90 5 0.83 0.83 300 DBSNa 0.68 96/2/2 0.21 5.68 Example 17 L-1790 5 0.83 0.81 300 DBSNa 0.68 94/2/4 0.21 5.68 Example 18 L-18 90 0.51.40 0.84 300 DBSNa 0.68 98/2/0 0.21 1.18 Example 19 L-19 90 0.5 1.400.84 300 DBSNa 0.68 97/2/1 0.21 1.18 Example 20 L-20 90 2.3 1.29 0.85300 DBSNa 0.68 96/2/2 0.21 2.98 Example 21 L-21 90 0.5 1.40 0.83 300DBSNa 0.68 96/2/2 0.21 1.18 Example 22 L-22 90 0.4 1.58 0.81 300 DBSNa0.68 96/2/2 0.21 1.08 Example 23 L-23 90 0.5 1.40 0.84 300 DBSNa 0.6894/2/4 0.21 1.18

TABLE 2 total amount water-based medium (A) of the organic organic acidinorganic emulsion (B) acid catalyst polyorgano- deionized catalyst acidcatalyst deionized emulsifier mixture of organosiloxane and the siloxanewater DBSH sulfuric acid water amount composition [part] feed rateemulsifier latex [part] [part] [part] pH [part] kind [part]DMC/DSMA/TEOS [part/min] [part] Comparative L-24 90 10 — 0.86 300 DBSNa0.68 98/2/0 0.83 10.67 Ex. 1 Comparative L-25 90 2 — 1.11 300 DBSNa 0.6897.5/0.5/2 0.83 2.67 Ex. 2 Reference L-26 90 0.1 1.52 0.79 300 DBSNa0.68 97.5/0.5/2 0.42 0.78 Ex. 3 Reference L-27 90 0.1 1.52 0.79 300DBSNa 0.68 97.5/0.5/2 0.21 0.78 Ex. 4 Reference L-28 90 0.1 1.52 0.79300 DBSNa 0.68 97.5/0.5/2 0.11 0.78 Ex 5 Comparative L-29 50 — — 6.51 40DBSH 1 97.5/0.5/2 1.11 1.00 Ex. 6 Comparative L-29-2 50 — — 6.55 40 DBSH1 97.5/0.5/2 0.21 1.00 Ex. 7 Comparative L-30 50 0.05 — 1.35 40 DBSH 197.5/0.5/2 1.11 1.05 Ex. 8 Comparative L-31 — — — — 200 DBSNa 0.6897.5/0.5/2 — 1.36 Ex. 9 DBSH 0.68

TABLE 3 average particle diameter polyorgano Dw solid siloxane Dw Dntandard content latex [nm] [nm] Dw/Dn deviation [%] Example 1 L-1 133 841.58 100 17.3 Example 2 L-2 154 145 1.06 47 18.2 Example 3 L-3 100 941.06 14 16.4 Example 4 L-4 110 100 1.10 36 17.8 Example 5 L-5 132 1181.12 25 17.7 Example 6 L-6 159 145 1.10 31 18.0 Example 7 L-7 130 1181.10 33 16.1 Example 8 L-8 130 124 1.05 17 17.1 Example 9 L-9 172 1551.11 30 17.4 Example 10 L-10 186 151 1.23 54 16.7 Example 11 L-11 171134 1.28 169 18.8 Example 12 L-12 132 118 1.12 23 17.3 Example 13 L-13129 108 1.19 34 17.6 Example 14 L-14 102 94 1.09 14 17.8 Example 15 L-15108 96 1.06 12 17.6 Example 16 L-16 100 94 1.06 13 17.9 Example 17 L-17104 99 1.05 12 17.7 Example 18 L-18 184 147 1.25 63 16.6 Example 19 L-19166 148 1.12 35 17.4 Example 20 L-20 122 96 1.27 41 17.9 Example 21 L-21154 133 1.16 30 16.9 Example 22 L-22 172 155 1.11 32 17.4 Example 23L-23 153 135 1.13 35 17.7 Comparative L-24 62 58 1.07 12 19.2 Ex. 1Comparative L-25 179 104 1.72 39 17.7 Ex. 2 Reference L-26 392 284 1.38102 17.4 Ex. 3 Reference L-27 402 293 1.37 139 16.5 Ex. 4 Reference L-28358 334 1.07 97 18.4 Ex. 5 Comparative L-29 470 168 2.80 238 40.0 Ex. 6Comparative L-29 357 144 2.48 238 40.0 Ex. 7 Comparative L-30 523 1383.79 231 36.0 Ex. 8 Comparative L-31 254 86 2.95 97 28.3 Ex. 9

Regarding the polyorganosiloxane latex in Example 1, the pH of thewater-based medium (A) was within the range of 0.1 to 1.2, and thereforeDw/Dn was 1.58. Namely, the particle diameter distribution was narrow.Further, as in Example 2, at a slower feeding rat of the emulsion (B), apolyorganosiloxane latex having a smaller Dw/Dn of 1.06 and a narrowerparticle diameter distribution could be obtained. In Example 3 in whichthe total amount of the organic acid catalyst and the emulsifier waschanged, the mass average particle diameter could be reduced while thenarrow particle diameter distribution was kept.

As in Examples 3 to 10 and 12 to 23, by changing the total amount of theorganic acid catalyst and the emulsifier, a polyorganosiloxane latexhaving any mass average particle diameter and a narrow particle diameterdistribution could be obtained.

In Example 11, polyoxyethylene distyrenated phenylether (made by KaoCorporation, trade name: EMULGEN A-500) that is a nonionic emulsifierwas used as an emulsifier for the emulsion (B) instead of DBSNa. Example11 shows that a polyorganosiloxane latex having a narrow particlediameter distribution could stably be produced.

In Comparative Example 1 in which the total amount of the organic acidcatalyst and the emulsifier was large, the mass average particlediameter of the polyorganosiloxane latex was less than 100 nm.

In Comparative Examples 6 to 8 in which the pH of the water-based medium(A) was more than 1.2, the mass average particle diameter ofpolyorganosiloxane was large, Dw/Dn was large, and the particle diameterdistribution was wide.

In Comparative Example 9 in which an emulsion (B) was not dropped, Dw/Dnof the obtained polyorganosiloxane was large and the particle diameterdistribution was wide.

Example 24 Production of Graft Copolymer (Ga-1)

7 parts of the polyorganosiloxane latex (L-12) obtained in Example 12(in terms of the solid content), 0.7 parts of dipotassiumalkenylsuccinate (made by Kao Corporation, trade name: LATEMUL ASK,hereinafter, abbreviated to “ASK”), and 197 parts of deionized water(including water in the polyorganosiloxane latex) were charged into aseparable flask equipped with a cooling condenser, and mixed. Next, amixture of 43 parts of n-butyl acrylate (n-BA), 0.3 parts of allylmethacrylate (AMA), 0.01 parts of 1,3-butylene dimethacrylate (1,3-BD),and 0.11 parts of t-butyl hydroperoxide (t-BH) was added into the flask.

A nitrogen stream was passed through the flask to replace the internalatmosphere with nitrogen, and the inner temperature was raised to 60° C.At this point, an aqueous solution including 0.000075 parts of ferroussulfate heptahydrate (Fe), 0.000225 parts of ethylenediaminetetraaceticacid disodium salt (EDTA), 0.2 parts of sodium formaldehyde sulfoxylate(SFS), and 8 parts of deionized water was added to initiate radicalpolymerization. Polymerization of the monomer component raised thetemperature of the solution to 78° C. Subsequently, the temperature waslowered to 75° C., and kept for 30 minutes. Polymerization of themonomer component was completed to obtain a latex of a composite polymer(ga-1) consisting of polyorganosiloxane (L-12) and a polymer of n-BA.

The composite polymer (ga-1) had a mass average particle diameter of 182nm. In 100% by mass of the composite polymer (in terms of the solidcontent), the proportion of the composite polymer particle having aparticle diameter of 400 nm or more was 0%, and the proportion of thecomposite polymer particle having a particle diameter of 100 nm or lesswas 0%.

Further, an aqueous solution including 0.2 parts of ASK, 0.001 parts ofFe, 0.003 parts of EDTA, 0.3 parts of SFS, and 24 parts of deionizedwater was added to the composite polymer (ga-1) latex. Next, as a firststage polymerization, a mixed solution of 10 parts of acrylonitrile(AN), 30 parts of styrene (ST), and 0.2 parts of t-BH was dropped over 1hour to perform polymerization. At this time, the temperature of thesolution was adjusted so as to be 80° C. when dropping was completed.After dropping was completed, the temperature was lowered to 75° C., andkept for 20 minutes. Next, as a second stage polymerization, a mixtureincluding 2.5 parts of AN, 7.5 parts of ST, 0.05 parts of t-BH, and 0.02parts of n-octylmercaptan (nOM) was dropped over 20 minutes to performpolymerization. After dropping was completed, the state where thetemperature was 75° C. was kept for 20 minutes. Then, 0.05 parts ofcumene hydroperoxide (CHP) was added, and further the state where thetemperature was 75° C. was kept for 30 minutes. Then, the temperaturewas lowered to obtain a latex of a graft copolymer (Ga-1) in which ANand ST were grafted to the composite polymer (ga-1).

Next, 150 parts of a 1% calcium acetate aqueous solution was heated to70° C., and 100 parts of the graft copolymer (Ga-1) latex was graduallydropped into the aqueous solution to solidify the graft copolymer(Ga-1). A precipitate was dehydrated, washed, and dried to obtain awhite powder of the graft copolymer (Ga-1).

Examples 25 to 32, and Comparative Examples 10 to 11 Production of GraftCopolymers (Ga-2) to (Ga-11)

Composite polymers (ga-2) to (ga-11) were obtained in the same manner asin Example 24 except that the kind and amount of polyorganosiloxane andthe amount of n-BA were changed as the condition shown in Table 4.Further, graft polymerization was performed using these compositepolymers and AN and ST at the amounts shown in Table 4 to obtain graftcopolymers (Ga-2) to (Ga-11).

Production Example 1 Production of Thermoplastic Resin (Ha-1)

Using 25 parts of AN and 75 parts of ST, a acrylonitrile-styrenecopolymer (Ha-1) whose reduced viscosity measured at 25° C. was 0.40dL/g was produced in an N,N-dimethylformamide solution by a knownsuspension polymerization method.

Production Examples 2 to 6 Production of Thermoplastic Resins (Ha-2 toHa-6)

Thermoplastic resins (Ha-2) to (Ha-6) were produced in the same manneras in Production Example 1 except that the kind and amount of thevinyl-based monomer were changed as the condition shown in Table 5. Themeasurement results of the reduced viscosity are shown in Table 5.

TABLE 4 composition of particle diameter of composite polymercomposition of grafted part mass proportion of proportion of compositepolymer first second average particle having a particle having a contentstage stage particle diameter of 100 nm diameter of 400 nm compositegraft kind of POSi/BA of POSi AN/ST AN/ST diameter or less or morepolymer copolymer POSi latex [part] [%] [part] [part] [nm] [%] [%]Example 24 ga-1 Ga-1 L-12 7/43 14 10/30 2.5/7.5 182 0 0 Example 25 ga-2Ga-2 L-12 5/45 10 10/30 2.5/7.5 185 3 0 Example 26 ga-3 Ga-3 L-12 7/4314 12/28 3/7 181 2 0 Example 27 ga-4 Ga-4 L-12 7/43 14  8/32 2/8 185 1.50 Example 28 ga-5 Ga-5 L-13 7/43 14 10/30 2.5/7.5 177 0 0 Example 29ga-6 Ga-6 L-15 7/43 14 10/30 2.5/7.5 128 7.4 0 Example 30 ga-7 Ga-7 L-167/43 14 10/30 2.5/7.5 127 1.9 0 Example 31 ga-8 Ga-8 L-17 7/43 14 10/302.5/7.5 122 6.8 0 Example 32 ga-9 Ga-9 L-14 7/43 14 10/30 2.5/7.5 1302.7 0 Comparative ga-10 Ga-10 L-24 1.75/48.25 3.5 10/30 2.5/7.5 150 00.9 Ex. 10 Comparative ga-11 Ga-11 L-24 7/43 14 10/30 2.5/7.5 114 22.7 0Ex. 11 POSi: polyorganosiloxane BA: n-butyl acrylate AN: acrylonitrileST: styrene

TABLE 5 Production thermoplastic composition [part] η sp/c Example resin(Ha) AN ST PMID αMS [dL/g] 1 Ha-1 25 75 0.40 2 Ha-2 28 72 0.62 3 Ha-3 3466 0.48 4 Ha-4 22 55 23 0.66 5 Ha-5 14 53 33 0.68 6 Ha-6 28 24 11 370.47 PMID: N-phenylmaleimide αMS: α-methylstyrene

Examples 33 to 47, and Comparative Examples 12 and 13 Production ofThermoplastic Resin Compositions (Ia-1 to Ia-17)

The graft copolymer and the thermoplastic resin composition were blendedat the composition shown in Table 6, and 0.5 parts ofethylenebisstearylamide (EBS), 0.03 parts of silicone oil (made by DowCorning Toray Co., Ltd., product name: SH-200) as additives, and 0.05parts of carbon black #960 (made by Mitsubishi Chemical Corporation) asa colorant were added, and mixed using a Henschel mixer. Next, themixture was fed to a volatilizing extruder (made by The Japan SteelWorks, Ltd., TEX-30a) whose barrel temperature was heated to 260° C.,and kneaded to obtain pellets of a resin composition. The melt volumerate of the pellets was measured. Further, the pellets were formed intoa test piece for evaluation using a 4-ounce injection molding machine(made by The Japan Steel Works, Ltd.) at 220 to 260° C., and the Charpyimpact strength (23° C.), MVR, bending strength, flexural modulus,deflection temperature under load, diffuse reflectance (brightness), andvibration welding properties were measured. The results are shown inTable 6 and Table 7.

In Examples 46 and 47, a polycarbonate resin (made by MitsubishiEngineering-Plastics Corporation, trade name: Iupilon S-2000F,hereinafter, abbreviated to “Ha-7”) was used as a thermoplastic resincomposition.

As shown in Examples 33 to 47 in Table 6 and Table 7, the graftcopolymers (Ga-1) to (Ga-9) according to the present invention canproduce a thermoplastic resin having high physical properties such asimpact strength and fluidity, low diffuse reflectance, remarkablebrightness, and high vibration welding properties. In contrast, inComparative Example 12, although the particle diameter of the compositepolymer meets the requirement of Claims, the thermoplastic resin showedreduced brightness because the mass average particle diameter (Dw) ofthe polyorganosiloxane (L-24) was small. In Comparative Example 13,impact strength and brightness were reduced because the mass averageparticle diameter (Dw) of the polyorganosiloxane (L-24) was small andthe composite polymer had a large proportion of the particle having aparticle diameter of 100 nm or less.

TABLE 6 Example 33 Example 34 Example 35 Example 36 Example 37 Example38 Example 39 Example 40 thermoplastic resin Ia-1 Ia-2 Ia-3 Ia-4 Ia-5Ia-6 Ia-7 Ia-8 composition (Ia) graft copolymer Ga-1 33 26 40 28 34 (Ga)[part] Ga-2 33 Ga-3 33 Ga-4 33 Ga-5 Ga-6 Ga-7 Ga-8 Ga-9 thermoplasticresin Ha-1 9 9 9 9 (Ha) Ha-2 8 8 8 8 36 22 [part] Ha-3 47 41 Ha-4 50 5050 50 Ha-5 38 38 Ha-6 25 25 Ha-7 Charpy impact kJ/m² 9.3 8.8 9.5 8.3 6.012.2 7.1 9.6 strength (23° C.) MVR cm³/10 min 5.1 5.0 4.2 5.5 8.9 4.017.0 14.0 bending strength MPa 79 81 80 81 87 70 82 74 flexural modulusMPa 2470 2500 2510 2530 2710 2200 2750 2490 deflection ° C. 95 95 95 9496 94 86 85 temperature under load diffuse reflectance % 3.8 4.3 4.1 4.33.5 4.3 3.0 3.0 (brightness) vibration welding rank 2 2 2 2 2 2 2 2

TABLE 7 Com- Com- Exam- Exam- parative parative Example 41 Example 42Example 43 Example 44 Example 45 ple 46 ple 47 Ex. 12 Ex. 13thermoplastic resin Ia-9 Ia-10 Ia-11 Ia-12 Ia-13 Ia-14 Ia-15 Ia-16 Ia-17composition (Ia) graft copolymer (Ga) Ga-1 33 33 [part] Ga-2 Ga-3 Ga-4Ga-5 33 Ga-6 33 Ga-7 33 Ga-8 33 Ga-9 33 Ga-10 33 Ga-11 33 thermoplasticresin Ha-1 9 9 9 9 9 9 (Ha) Ha-2 29 8 8 8 8 47 27 8 8 [part] Ha-3 Ha-450 50 50 50 50 50 Ha-5 38 Ha-6 Ha-7 20 40 Charpy impact kJ/m² 9.7 7.87.5 7.6 7.1 21 50 7.3 5.1 strength (23° C.) MVR cm³/10 min 5.8 4.5 4.54.6 4.4 12.1 7.7 4.8 4.3 bending strength MPa 80 83 82 83 81 71 71 80 84flexural modulus MPa 2560 2490 2480 2480 2440 2200 1990 2490 2500deflection temperature ° C. 94 93 94 94 94 87 93 95 95 under loaddiffuse reflectance % 4.3 3.6 3.7 3.7 4.5 3.8 4.4 5.1 5.1 (brightness)vibration welding rank 2 2 2 2 2 2 2 2 2 Ha-7: a polycarbonate resin(Mitsubishi Engineering-Plastics Corporation, trade name: IupilonS-2000F)

Example 48 Production of Graft Copolymer (Gb-1)

A mixture of 25 parts of the polyorganosiloxane latex (L-12) obtained inExample 12 (in terms of the solid content), 25 parts of n-BA, 0.2 partsof AMA, 0.05 parts of 1,3-BD, 0.063 parts of t-BH, and 208 parts ofdeionized water (including water in the polyorganosiloxane latex) wascharged into a separable flask equipped with a cooling condenser. Next,a nitrogen stream was passed through the flask to replace theatmosphere, and the inner temperature was raised to 60° C. At thispoint, an aqueous solution including 0.00005 parts of Fe, 0.00015 partsof EDTA, 0.12 parts of SFS, and 4 parts of deionized water was added toinitiate polymerization. After the maximum point of the innertemperature was recognized from heat generated by polymerization of themonomer component, the temperature was lowered to 65° C., and kept for30 minutes. Then, polymerization of the monomer component was completedto obtain a latex of a composite polymer (gb-1) consisting ofpolyorganosiloxane (L-12) and a polymer of n-BA. Regarding the obtainedcomposite polymer (gb-1), the mass average particle diameter was 140 nm,the proportion of the composite polymer particle having a particlediameter less than 100 nm was 7%, and the proportion of the compositepolymer particle having a particle diameter of 300 nm or more was 1.3%.

Next, an aqueous solution including 0.001 parts of Fe, 0.003 parts ofEDTA, 0.3 parts of SFS, 0.55 parts of DBSNa, and 11 parts of deionizedwater was added to the composite polymer (gb-1) latex. Further, while amixed solution of 12.5 parts of AN, 37.5 parts of ST, and 0.23 parts oft-BH was dropped over 100 minutes, the temperature was raised to 80° C.After dropping was completed, the state where the temperature was 80° C.was kept for 20 minutes. Then, 0.05 parts of CHP was added, and thetemperature was kept for 30 minutes, and then lowered to obtain a graftcopolymer (Gb-1) latex.

Meanwhile, 140 parts of an aqueous solution in which 6% calcium acetatewas dissolved was prepared, and heated to 85° C. Next, while the aqueoussolution was stirred, the graft copolymer (Gb-1) latex (100 parts of thesolid content) was gradually dropped into the aqueous solution tosolidify the graft copolymer (Gb-1). Further, the temperature was raisedto 95° C., and kept for 5 minutes. The obtained solidified product wasdehydrated, washed, and dried to obtain a powder of the graft copolymer(Gb-1).

Examples 49 to 60, and Comparative Examples 14 to 17 Production of GraftCopolymers (Gb-2) to (Gb-17)

Composite polymers (gb-2) to (gb-17) were obtained in the same manner asin Example 48 except that the kind and amount of polyorganosiloxane andthe amount of n-BA were changed as the condition shown in Table 8.Further, using these composite polymers and AN and ST at the amountsshown in Table 8, graft polymerization was performed to obtain graftcopolymers (Gb-2) to (Gb-17). In Comparative Example 16, a mixture of 83parts of (L-24) and 17 parts of (L-31) in terms of the solid content wasused as the polyorganosiloxane latex (L-32). The mass average particlediameter (Dw) of the polyorganosiloxane (L-32) was 101 nm, the numberaverage particle diameter (Dn) was 58 nm, and the particle diameterdistribution (Dw/Dn) expressed as the ratio thereof was 1.74.

Production Examples 7 to 9 Production of Thermoplastic Resins (Hb-1) to(Hb-3)

Using the kind and amount of the vinyl-based monomers shown in Table 9,copolymers (Hb-1) to (Hb-3) were produced by a known suspensionpolymerization method. The reduced viscosity of each copolymer measuredin an N,N-dimethylformamide solution at 25° C. was shown in Table 9.

TABLE 8 particle diameter of composite polymer proportion of compositionof composition proportion of particle composite polymer of mass averageparticle havin a diameter content grafted part particle having adiameter of 300 nm or composite graft kind of POSi/BA of POSi AN STdiameter of 100 nm or less more polymer copolymer POSi latex [part] [%][part] [part] [nm] [%] [%] Example 48 gb-1 Gb-1 L-12 25/25 50 12.5 37.5140 7.0 1.3 Example 49 gb-2 Gb-2 L-12 10/40 20 12.5 37.5 170 0.8 4.9Example 50 gb-3 Gb-3 L-12 15/35 30 12.5 37.5 160 6.1 6.0 Example 51 gb-4Gb-4 L-12 20/30 40 12.5 37.5 150 1.1 1.6 Example 52 gb-5 Gb-5 L-12 35/1570 12.5 37.5 135 12.9 2.0 Example 53 gb-6 Gb-6 L-13 25/25 50 12.5 37.5140 8.9 0.8 Example 54 gb-7 Gb-7 L-19 25/25 50 12.5 37.5 160 3.4 6.7Example 55 gb-8 Gb-8 L-20 25/25 50 12.5 37.5 140 11.7 2.1 Example 56gb-9 Gb-9 L-21 25/25 50 12.5 37.5 160 0.7 2.1 Example 57 gb-10 Gb-10L-22 25/25 50 12.5 37.5 190 0.0 5.3 Example 58 gb-11 Gb-11 L-23 25/25 5012.5 37.5 160 4.1 5.0 Example 59 gb-12 Gb-12 L-12 20/30 40 15.0 35.0 1501.1 1.6 Example 60 gb-13 Gb-13 L-12 24/36 40 12.0 28.0 150 4.3 1.2Comparative gb-14 Gb-14 L-24 25/25 50 12.5 37.5 70 88.5 0.1 Ex. 14Comparative gb-15 Gb-15 L-31 25/25 50 12.5 37.5 210 2.6 20.7 Ex. 15Comparative gb-16 Gb-16 L-32 25/25 50 12.5 37.5 90 66.9 1.9 Ex. 16Comparative gb-17 Gb-17 L-24  7/43 14 12.5 37.5 90 47.9 0.0 Ex. 17

TABLE 9 Production thermoplastic composition [part] η sp/c Example resin(Hb) AN ST PMID [dL/g] 7 Hb - 1 34 66 0.62 8 Hb - 2 29 71 0.61 9 Hb - 348 52 0.64

Examples 61 to 78, and Comparative Examples 18 to 22 Production ofThermoplastic Resin Compositions (Ib-1 to Ib-23)

The graft copolymers (Gb-1) to (Gb-17) and the thermoplastic resins(Hb-1) to (Hb-3) were blended at the corresponding composition shown inTables 10 to 12. Further, 0.3 parts of EBS as a lubricant and 0.5 partsof carbon black #960 as a colorant were mixed using a Henschel mixer.Next, the mixture was fed into a volatilizing twin screw extruder (madeby Ikegai Corp., PCM-30) whose barrel temperature was heated to 230° C.,and kneaded to produce pellets of each of the thermoplastic resincompositions (Ib-1) to (Ib-23). The melt volume rate of each pellet wasmeasured.

The pellets were formed into a test piece for evaluation with a 4-ounceinjection molding machine (made by The Japan Steel Works, Ltd.) at 230°C. The measurement results of the melt volume rate, flexural modulus,deflection temperature under load, Charpy impact strengths at 23° C. and−30° C., and color developability are shown in Tables 10 to 12. In Table12, a polycarbonate resin (made by Mitsubishi Engineering-PlasticsCorporation, trade name: Iupilon S-3000) was used as Hb-4.

The thermoplastic resin compositions in Examples 61 to 78 using thegraft copolymers (Gb-1) to (Gb-13) according to the present inventioncould have a good balance between mechanical strength such as impactstrength and flexural modulus, in particular Charpy impact strength at−30° C., and color developability. Meanwhile, in Comparative Examples18, 21, and 22, the polyorganosiloxane (L-24) and the composite polymers(gb-14) and (gb-17) had a small mass average particle diameter (Dw), andthe composite polymer had a large proportion of the particle having aparticle diameter of 100 nm or less. For this reason, Charpy impactstrength at −30° C. was low. Further, in Comparative Example 19, themass average particle diameter (Dw) of the polyorganosiloxane (L-31) waslarge, and the composite polymer had a large proportion of the particlehaving a particle diameter of 300 nm or more. For this reason, Charpyimpact strength at −30° C. was low, and color developability wasworsened. In Comparative Example 20, the particle diameter distribution(Dw/Dn) of the polyorganosiloxane (L-32) was large, and therefore themass average particle diameter (Dw) of the composite polymer (gb-16) wassmall, and Charpy impact strength at −30° C. was low.

TABLE 10 Example Example Example 61 62 63 Example 64 Example 65 Example66 Example 67 Example 68 thermoplastic resin composition (Ib) Ib-1 Ib-2Ib-3 Ib-4 Ib-5 Ib-6 Ib-7 Ib-8 graft copolymer (Gb) kind Gb-1 Gb-2 Gb-3Gb-4 Gb-5 Gb-6 Gb-7 Gb-8 amount [part] 42 42 42 42 42 42 42 42thermoplastic resin (Hb) kind Hb-1 Hb-1 Hb-1 Hb-1 Hb-1 Hb-1 Hb-1 Hb-1amount [part] 58 58 58 58 58 58 58 58 rubber content % 21 21 21 21 21 2121 21 MVR cm³/10 min 11 13 12 13 10 12 12 13 flexural modulus MPa 21802210 2230 2240 2240 2250 2150 2230 deflection temperature ° C. 82 83 8383 83 83 81 83 under load Charpy impact   23° C. kJ/m² 22 21 23 23 16 2421 22 strength −30° C. 12 8 9 11 9 12 12 11 color developability (L*) 1819 19 19 19 18 20 18

TABLE 11 Example Example Example Comparative Comparative Comparative 6970 71 Example 72 Example 73 Ex. 18 Ex. 19 Ex. 20 thermoplastic resincomposition (Ib) Ib-9 Ib-10 Ib-11 Ib-12 Ib-13 Ib-14 Ib-15 Ib-16 graftcopolymer (Gb) kind Gb-9 Gb-10 Gb-11 Gb-12 Gb-13 Gb-14 Gb-15 Gb-16amount [part] 42 42 42 42 35 42 42 42 thermoplastic resin (Hb) kind Hb-1Hb-1 Hb-1 Hb-1 Hb-1 Hb-1 Hb-1 Hb-1 amount [part] 58 58 58 58 65 58 58 58rubber content % 21 21 21 21 21 21 21 21 MVR cm³/10 min 13 12 12 9 12 1014 13 flexural modulus MPa 2180 2190 2220 2240 2270 2280 2310 2330deflection temperature ° C. 82 82 83 83 83 83 83 83 under load Charpyimpact   23° C. kJ/m² 18 18 15 25 24 8 7 13 strength −30° C. 11 11 8 1211 3 4 5 color developability (L*) 20 21 19 17 14 13 25 18

TABLE 12 Example Example Comparative Comparative 74 Example 75 76Example 77 Example 78 Ex. 21 Ex. 22 thermoplastic resin composition (Ib)Ib-17 Ib-18 Ib-19 Ib-20 Ib-21 Ib-22 Ib-23 graft copolymer (Gb) kind Gb-4Gb-4 Gb-4 Gb-4 Gb-4 Gb-17 Gb-17 amount [part] 30 34 38 42 44 42 44thermoplastic resin (Hb) Hb-1 70 66 62 48 48 [part] Hb-2 37 37 Hb-3 1919 Hb-4 10 10 rubber content % 15 17 19 21 22 21 22 MVR cm³/10 min 17 1613 8 3 8 3 flexural modulus MPa 2700 2560 2420 2150 2120 2140 2100deflection temperature ° C. 84 83 83 86 92 86 92 under load Charpyimpact   23° C. kJ/m² 12 16 21 19 15 17 13 strength −30° C. 5 6 9 10 6 52 color developability (L*) 17 18 19 20 21 17 18 Hb-4: a polycarbonateresin (Mitsubishi Engineering-Plastics Corporation, trade name: IupilonS-3000)

INDUSTRIAL APPLICABILITY

The polyorganosiloxane latex according to the present invention can bewidely used as raw materials for resin additives, fiber treatmentagents, mold release agents, cosmetics, antifoaming agents, additivesfor a coating material, and the like. The graft copolymer obtained usingthe polyorganosiloxane latex according to the present invention is inparticular useful as raw materials for resin additives because athermoplastic resin composition having a narrow particle distributionand suitable properties for intended applications can be produced.

1. A polyorganosiloxane latex, wherein a mass average particle diameter(Dw) of a polyorganosiloxane particle is 100 to 200 nm, and wherein aratio (Dw/Dn) of the mass average particle diameter (Dw) to a numberaverage particle diameter (Dn) of the particle is 1.0 to 1.7.
 2. Thepolyorganosiloxane latex according to claim 1, wherein a standarddeviation of the mass average particle diameter (Dw) of thepolyorganosiloxane particle is 0 to
 80. 3. The polyorganosiloxane latexaccording to claim 1, wherein a proportion of the polyorganosiloxaneparticle having a particle diameter less than 50 nm is 5% by mass orless based on the total amount of the particle, and wherein a proportionof the polyorganosiloxane particle having a particle diameter of 300 nmor more is 20% by mass or less based on the total amount of theparticle.
 4. A polyorganosiloxane-containing vinyl-based copolymerobtained by polymerizing one or more vinyl-based monomers in thepresence of the polyorganosiloxane latex according to claim
 1. 5. Thepolyorganosiloxane-containing vinyl-based copolymer according to claim4, wherein a mass average particle diameter (Dw) of a particle in thepolyorganosiloxane-containing vinyl-based copolymer is 110 nm to 800 nm,and a ratio (Dw/Dn) of the mass average particle diameter (Dw) to anumber average particle diameter (Dn) of the particle is 1.0 to 2.0. 6.The polyorganosiloxane-containing vinyl-based copolymer according toclaim 4, wherein the vinyl-based monomer is an acrylic acid ester.
 7. Agraft copolymer (G) obtained by graft polymerizing one or morevinyl-based monomers in the presence of thepolyorganosiloxane-containing vinyl-based copolymer according to claim4.
 8. The graft copolymer (G) according to claim 7, wherein a moldedbody obtained by molding the following composition exhibits thefollowing performance (1) and (2) when evaluated under the followingmeasurement conditions: (1) a Charpy impact strength at 23° C. is 6kJ/m² or more, and (2) a diffuse reflectance is 5% or less; test pieceproduction conditions of: (a) 33 parts by mass of a graft copolymer(Ga), (b) 9 parts by mass of an acrylonitrile-styrene copolymercomprising 25% by mass of an acrylonitrile unit and 75% by mass of astyrene unit and having a reduced viscosity (ηsp/c) of 0.40 dL/g in anN,N-dimethylformamide solution of 0.2 g/dL at 25° C., (c) 9 parts bymass of an acrylonitrile-styrene copolymer comprising 28% by mass of anacrylonitrile unit and 72% by mass of a styrene unit and having areduced viscosity of 0.62 dL/g in an N,N-dimethylformamide solution of0.2 g/dL at 25° C., (d) 50 parts by mass of anacrylonitrile-styrene-N-phenylmaleimide copolymer comprising 22% by massof an acrylonitrile unit, 55% by mass of a styrene unit, and 23% by massof an N-phenylmaleimide unit and having a reduced viscosity of 0.40 dL/gin an N,N-dimethylformamide solution of 0.2 g/dL at 25° C., (e) 0.5parts by mass of ethylenebisstearylamide, (f) 0.03 parts by mass ofsilicone oil, and (g) 0.05 parts by mass of carbon black; wherein theseven materials (a) to (g) above are blended and kneaded using avolatilizing extruder whose barrel is heated to a temperature of 260° C.to obtain pellets; the pellets are molded using a 4-ounce injectionmolding machine in conditions of a cylinder temperature of 260° C. and amold temperature of 60° C. to obtain a test piece 1 with a length of 80mm, a width of 10 mm and a thickness of 4 mm; and a plate-like moldedbody 2 a length of 100 mm, a width of 100 mm and a thickness of 2 mm isobtained in the same manner as above in conditions of a cylindertemperature of 260° C., a mold temperature of 60° C., and an injectionrate of 5 g/sec; Charpy impact strength measurement conditions of:measurement is conducted on a V-notched test piece 1 that is left undera 23° C. atmosphere for 12 hours or more by a method according to ISO179; diffuse reflectance measurement conditions of: a 50 nm aluminumfilm is formed through a direct deposition on the surface of the moldedbody 2 by a vacuum deposition method in conditions of a degree of vacuumof 6.0×10⁻³ Pa and a film forming rate of 10 angstroms/sec; and adiffuse reflectance (%) of the obtained molded body is measured using areflectance meter.
 9. The graft copolymer (Ga) according to claim 8,comprising 5 to 25% by mass of polyorganosiloxane based on 100% by massof a polyorganosiloxane-containing vinyl-based copolymer, wherein amixture of a vinyl cyanide-based monomer and an aromatic vinyl-basedmonomer is graft polymerized with the polyorganosiloxane-containingvinyl-based copolymer, wherein the polyorganosiloxane-containingvinyl-based copolymer has a mass average particle diameter (Dw) of 120to 200 nm, wherein a proportion of a particle having a particle diameterof 100 nm or less is 15% by mass or less based on the total amount ofthe particle, and wherein a proportion of the particle having a particlediameter of 400 nm or more is 1% by mass or less based on the totalamount of the particle.
 10. The graft copolymer (Ga) according to claim9, wherein the polyorganosiloxane contains 0.5 to 5 parts by mass of acomponent derived from a siloxane-based crosslinking agent based on 100parts by mass of the organosiloxane.
 11. A thermoplastic resincomposition (Ia) comprising the graft copolymer (Ga) according to claim8, and a thermoplastic resin (Ha) except for the graft copolymer (Ga).12. The thermoplastic resin composition (Ia) according to claim 11,wherein the thermoplastic resin (Ha) is a copolymer comprising 0 to 40%by mass of a vinyl cyanide-based monomer unit, 40 to 80% by mass of anaromatic vinyl-based monomer unit, and 0 to 60% by mass of anothermonomer unit whose monomer is copolymerizable with these monomers.
 13. Amolded body obtained by molding the thermoplastic resin composition (Ia)according to claim
 11. 14. A lamp housing for vehicle lightingcomprising a molded body obtained by molding the thermoplastic resincomposition (Ia) according to claim
 11. 15. The graft copolymer (G)according to claim 7, wherein a molded body obtained by molding thefollowing composition exhibits the following performance (1) and (2)when evaluated under the following measurement conditions: (1) L* is 24or less, and (2) a Charpy impact strength at −30° C. is 6 kJ/m² or more;test piece production conditions of: (a) 42 parts by mass of a graftcopolymer (Gb), (b) 58 parts by mass of an acrylonitrile-styrenecopolymer comprising 34% by mass of an acrylonitrile unit and 66% bymass of a styrene unit and having a reduced viscosity (ηsp/c) of 0.62dL/g in an N,N-dimethylformamide solution of 0.2 g/dL at 25° C., (c) 0.3parts by mass of ethylenebisstearylamide, and (d) 0.5 parts by mass ofcarbon black; wherein the four materials (a) to (d) above are blendedand kneaded using a volatilizing extruder whose barrel is heated to atemperature of 230° C. to obtain pellets; the pellets are molded using a4-ounce injection molding machine in conditions of a cylindertemperature of 230° C. and a mold temperature of 60° C. to obtain a testpiece 3 with a length of 80 mm, a width of 10 mm and a thickness of 4 mmand a tensile test piece 4 a length of 170 mm, a width of 20 mm and athickness of 4 mm; Charpy impact strength measurement conditions of:measurement is conducted on a V-notched test piece 3 that is left undera −30° C. atmosphere for 12 hours or more by a method according to ISO179; L*measurement conditions of: L* is measured for the tensile testpiece 4 using a spectrophotometer on a side opposite to a gate.
 16. Thegraft copolymer (Gb) according to claim 15, comprising 15 to 80% by massof polyorganosiloxane based on 100% by mass of apolyorganosiloxane-containing vinyl-based copolymer, wherein a mixtureof a vinyl cyanide-based monomer and an aromatic vinyl-based monomer isgraft polymerized with the polyorganosiloxane-containing vinyl-basedcopolymer, wherein the polyorganosiloxane-containing vinyl-basedcopolymer has a mass average particle diameter (Dw) of 110 to 250 nm,wherein a proportion of a particle having a particle diameter less than100 nm is 20% by mass or less based on the total amount of the particle,and wherein a proportion of the particle diameter of 300 nm or more is20% by mass or less based on the total amount of the particle.
 17. Thegraft copolymer (Gb) according to claim 16, wherein thepolyorganosiloxane contains 0.5 to 3 parts by mass of a componentderived from a siloxane-based crosslinking agent based on 100 parts bymass of the organosiloxane.
 18. A thermoplastic resin composition (Ib)comprising the graft copolymer (Gb) according to claim 15 and athermoplastic resin (Hb) except for the graft copolymer (Gb).
 19. Thethermoplastic resin composition (Ib) according to claim 18, wherein thethermoplastic resin (Hb) is a copolymer comprising 0 to 40% by mass of avinyl cyanide-based monomer unit, 40 to 80% by mass of an aromaticvinyl-based monomer unit, and 0 to 60% by mass of another vinyl-basedmonomer unit whose monomer is copolymerizable with these monomers.
 20. Amolded body obtained by molding the thermoplastic resin composition (Ib)according to claim
 18. 21. A method of producing a polyorganosiloxanelatex, the method comprising a step of dropping an emulsion (B)comprising organosiloxane, an emulsifier, and water into a water-basedmedium (A) comprising water, an organic acid catalyst, and an inorganicacid catalyst; and a step of performing polymerization, wherein a totalamount of the organic acid catalyst and the emulsifier is 0.5 to 6 partsby mass based on 100 parts by mass of the organosiloxane, wherein the pHof the water-based medium (A) measured at 25° C. is within the range of0 to 1.2, and wherein the dropping rate of the emulsion (B) is a ratesuch that an amount of organosiloxane to be fed is 0.5 [parts bymass/min] or less when a total amount of organosiloxane to be used is100 parts by mass.